Extensible Markup Language (XML) 1.0

From 891c29af147fcbe6c4dd5d8ffbbb426665d4b558 Mon Sep 17 00:00:00 2001 From: Lorry Date: Mon, 21 May 2012 16:44:15 +0100 Subject: Tarball conversion --- samples/REC-xml-19980210.xml | 4197 ++++++++++++++++++++++++++++++++++++++++++ samples/canonical | 124 ++ samples/canontst.xml | 20 + samples/ctest.dtd | 2 + samples/xmlcomments | 44 + samples/xmlfilter | 329 ++++ samples/xmlstats | 186 ++ 7 files changed, 4902 insertions(+) create mode 100644 samples/REC-xml-19980210.xml create mode 100755 samples/canonical create mode 100644 samples/canontst.xml create mode 100644 samples/ctest.dtd create mode 100755 samples/xmlcomments create mode 100755 samples/xmlfilter create mode 100755 samples/xmlstats (limited to 'samples') diff --git a/samples/REC-xml-19980210.xml b/samples/REC-xml-19980210.xml new file mode 100644 index 0000000..c108ff5 --- /dev/null +++ b/samples/REC-xml-19980210.xml @@ -0,0 +1,4197 @@ + + + + + + + + + + + + + + + + +"> + +'"> + + + + + + + + + +amp, +lt, +gt, +apos, +quot"> + + + + + +]> + + + + + +

+Extensible Markup Language (XML) 1.0 + +REC-xml-&iso6.doc.date; +W3C Recommendation +&draft.day;&draft.month;&draft.year; + + + +http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date; + +http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.xml + +http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.html + +http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.pdf + +http://www.w3.org/TR/1998/REC-xml-&iso6.doc.date;.ps + + + +http://www.w3.org/TR/REC-xml + + + +http://www.w3.org/TR/PR-xml-971208 + + + +Tim Bray +Textuality and Netscape +tbray@textuality.com +Jean Paoli +Microsoft +jeanpa@microsoft.com +C. M. Sperberg-McQueen +University of Illinois at Chicago +cmsmcq@uic.edu + + +

The Extensible Markup Language (XML) is a subset of +SGML that is completely described in this document. Its goal is to +enable generic SGML to be served, received, and processed on the Web +in the way that is now possible with HTML. XML has been designed for +ease of implementation and for interoperability with both SGML and +HTML.

+ + +

This document has been reviewed by W3C Members and +other interested parties and has been endorsed by the +Director as a W3C Recommendation. It is a stable +document and may be used as reference material or cited +as a normative reference from another document. W3C's +role in making the Recommendation is to draw attention +to the specification and to promote its widespread +deployment. This enhances the functionality and +interoperability of the Web.

+This document specifies a syntax created by subsetting an existing, +widely used international text processing standard (Standard +Generalized Markup Language, ISO 8879:1986(E) as amended and +corrected) for use on the World Wide Web. It is a product of the W3C +XML Activity, details of which can be found at http://www.w3.org/XML. A list of +current W3C Recommendations and other technical documents can be found +at http://www.w3.org/TR. +

This specification uses the term URI, which is defined by , a work in progress expected to update and . +

The list of known errors in this specification is +available at +http://www.w3.org/XML/xml-19980210-errata.

Please report errors in this document to +xml-editor@w3.org. +

+ + + + +

Chicago, Vancouver, Mountain View, et al.: +World-Wide Web Consortium, XML Working Group, 1996, 1997.

+ + +

Created in electronic form.

+ + +English +Extended Backus-Naur Form (formal grammar) + + + +1997-12-03 : CMSMcQ : yet further changes +1997-12-02 : TB : further changes (see TB to XML WG, +2 December 1997) +1997-12-02 : CMSMcQ : deal with as many corrections and +comments from the proofreaders as possible: +entify hard-coded document date in pubdate element, +change expansion of entity WebSGML, +update status description as per Dan Connolly (am not sure +about refernece to Berners-Lee et al.), +add 'The' to abstract as per WG decision, +move Relationship to Existing Standards to back matter and +combine with References, +re-order back matter so normative appendices come first, +re-tag back matter so informative appendices are tagged informdiv1, +remove XXX XXX from list of 'normative' specs in prose, +move some references from Other References to Normative References, +add RFC 1738, 1808, and 2141 to Other References (they are not +normative since we do not require the processor to enforce any +rules based on them), +add reference to 'Fielding draft' (Berners-Lee et al.), +move notation section to end of body, +drop URIchar non-terminal and use SkipLit instead, +lose stray reference to defunct nonterminal 'markupdecls', +move reference to Aho et al. into appendix (Tim's right), +add prose note saying that hash marks and fragment identifiers are +NOT part of the URI formally speaking, and are NOT legal in +system identifiers (processor 'may' signal an error). +Work through: +Tim Bray reacting to James Clark, +Tim Bray on his own, +Eve Maler, + +NOT DONE YET: +change binary / text to unparsed / parsed. +handle James's suggestion about < in attriubte values +uppercase hex characters, +namechar list, + +1997-12-01 : JB : add some column-width parameters +1997-12-01 : CMSMcQ : begin round of changes to incorporate +recent WG decisions and other corrections: +binding sources of character encoding info (27 Aug / 3 Sept), +correct wording of Faust quotation (restore dropped line), +drop SDD from EncodingDecl, +change text at version number 1.0, +drop misleading (wrong!) sentence about ignorables and extenders, +modify definition of PCData to make bar on msc grammatical, +change grammar's handling of internal subset (drop non-terminal markupdecls), +change definition of includeSect to allow conditional sections, +add integral-declaration constraint on internal subset, +drop misleading / dangerous sentence about relationship of +entities with system storage objects, +change table body tag to htbody as per EM change to DTD, +add rule about space normalization in public identifiers, +add description of how to generate our name-space rules from +Unicode character database (needs further work!). + +1997-10-08 : TB : Removed %-constructs again, new rules +for PE appearance. +1997-10-01 : TB : Case-sensitive markup; cleaned up +element-type defs, lotsa little edits for style +1997-09-25 : TB : Change to elm's new DTD, with +substantial detail cleanup as a side-effect +1997-07-24 : CMSMcQ : correct error (lost *) in definition +of ignoreSectContents (thanks to Makoto Murata) +Allow all empty elements to have end-tags, consistent with +SGML TC (as per JJC). +1997-07-23 : CMSMcQ : pre-emptive strike on pending corrections: +introduce the term 'empty-element tag', note that all empty elements +may use it, and elements declared EMPTY must use it. +Add WFC requiring encoding decl to come first in an entity. +Redefine notations to point to PIs as well as binary entities. +Change autodetection table by removing bytes 3 and 4 from +examples with Byte Order Mark. +Add content model as a term and clarify that it applies to both +mixed and element content. + +1997-06-30 : CMSMcQ : change date, some cosmetic changes, +changes to productions for choice, seq, Mixed, NotationType, +Enumeration. Follow James Clark's suggestion and prohibit +conditional sections in internal subset. TO DO: simplify +production for ignored sections as a result, since we don't +need to worry about parsers which don't expand PErefs finding +a conditional section. +1997-06-29 : TB : various edits +1997-06-29 : CMSMcQ : further changes: +Suppress old FINAL EDIT comments and some dead material. +Revise occurrences of % in grammar to exploit Henry Thompson's pun, +especially markupdecl and attdef. +Remove RMD requirement relating to element content (?). + +1997-06-28 : CMSMcQ : Various changes for 1 July draft: +Add text for draconian error handling (introduce +the term Fatal Error). +RE deleta est (changing wording from +original announcement to restrict the requirement to validating +parsers). +Tag definition of validating processor and link to it. +Add colon as name character. +Change def of %operator. +Change standard definitions of lt, gt, amp. +Strip leading zeros from #x00nn forms. +1997-04-02 : CMSMcQ : final corrections of editorial errors +found in last night's proofreading. Reverse course once more on +well-formed: Webster's Second hyphenates it, and that's enough +for me. +1997-04-01 : CMSMcQ : corrections from JJC, EM, HT, and self +1997-03-31 : Tim Bray : many changes +1997-03-29 : CMSMcQ : some Henry Thompson (on entity handling), +some Charles Goldfarb, some ERB decisions (PE handling in miscellaneous +declarations. Changed Ident element to accept def attribute. +Allow normalization of Unicode characters. move def of systemliteral +into section on literals. +1997-03-28 : CMSMcQ : make as many corrections as possible, from +Terry Allen, Norbert Mikula, James Clark, Jon Bosak, Henry Thompson, +Paul Grosso, and self. Among other things: give in on "well formed" +(Terry is right), tentatively rename QuotedCData as AttValue +and Literal as EntityValue to be more informative, since attribute +values are the only place QuotedCData was used, and +vice versa for entity text and Literal. (I'd call it Entity Text, +but 8879 uses that name for both internal and external entities.) +1997-03-26 : CMSMcQ : resynch the two forks of this draft, reapply +my changes dated 03-20 and 03-21. Normalize old 'may not' to 'must not' +except in the one case where it meant 'may or may not'. +1997-03-21 : TB : massive changes on plane flight from Chicago +to Vancouver +1997-03-21 : CMSMcQ : correct as many reported errors as possible. + +1997-03-20 : CMSMcQ : correct typos listed in CMSMcQ hand copy of spec. +1997-03-20 : CMSMcQ : cosmetic changes preparatory to revision for +WWW conference April 1997: restore some of the internal entity +references (e.g. to docdate, etc.), change character xA0 to   +and define nbsp as  , and refill a lot of paragraphs for +legibility. +1996-11-12 : CMSMcQ : revise using Tim's edits: +Add list type of NUMBERED and change most lists either to +BULLETS or to NUMBERED. +Suppress QuotedNames, Names (not used). +Correct trivial-grammar doc type decl. +Rename 'marked section' as 'CDATA section' passim. +Also edits from James Clark: +Define the set of characters from which [^abc] subtracts. +Charref should use just [0-9] not Digit. +Location info needs cleaner treatment: remove? (ERB +question). +One example of a PI has wrong pic. +Clarify discussion of encoding names. +Encoding failure should lead to unspecified results; don't +prescribe error recovery. +Don't require exposure of entity boundaries. +Ignore white space in element content. +Reserve entity names of the form u-NNNN. +Clarify relative URLs. +And some of my own: +Correct productions for content model: model cannot +consist of a name, so "elements ::= cp" is no good. + +1996-11-11 : CMSMcQ : revise for style. +Add new rhs to entity declaration, for parameter entities. +1996-11-10 : CMSMcQ : revise for style. +Fix / complete section on names, characters. +Add sections on parameter entities, conditional sections. +Still to do: Add compatibility note on deterministic content models. +Finish stylistic revision. +1996-10-31 : TB : Add Entity Handling section +1996-10-30 : TB : Clean up term & termdef. Slip in +ERB decision re EMPTY. +1996-10-28 : TB : Change DTD. Implement some of Michael's +suggestions. Change comments back to //. Introduce language for +XML namespace reservation. Add section on white-space handling. +Lots more cleanup. +1996-10-24 : CMSMcQ : quick tweaks, implement some ERB +decisions. Characters are not integers. Comments are /* */ not //. +Add bibliographic refs to 10646, HyTime, Unicode. +Rename old Cdata as MsData since it's only seen +in marked sections. Call them attribute-value pairs not +name-value pairs, except once. Internal subset is optional, needs +'?'. Implied attributes should be signaled to the app, not +have values supplied by processor. +1996-10-16 : TB : track down & excise all DSD references; +introduce some EBNF for entity declarations. +1996-10-?? : TB : consistency check, fix up scraps so +they all parse, get formatter working, correct a few productions. +1996-10-10/11 : CMSMcQ : various maintenance, stylistic, and +organizational changes: +Replace a few literals with xmlpio and +pic entities, to make them consistent and ensure we can change pic +reliably when the ERB votes. +Drop paragraph on recognizers from notation section. +Add match, exact match to terminology. +Move old 2.2 XML Processors and Apps into intro. +Mention comments, PIs, and marked sections in discussion of +delimiter escaping. +Streamline discussion of doctype decl syntax. +Drop old section of 'PI syntax' for doctype decl, and add +section on partial-DTD summary PIs to end of Logical Structures +section. +Revise DSD syntax section to use Tim's subset-in-a-PI +mechanism. +1996-10-10 : TB : eliminate name recognizers (and more?) +1996-10-09 : CMSMcQ : revise for style, consistency through 2.3 +(Characters) +1996-10-09 : CMSMcQ : re-unite everything for convenience, +at least temporarily, and revise quickly +1996-10-08 : TB : first major homogenization pass +1996-10-08 : TB : turn "current" attribute on div type into +CDATA +1996-10-02 : TB : remould into skeleton + entities +1996-09-30 : CMSMcQ : add a few more sections prior to exchange + with Tim. +1996-09-20 : CMSMcQ : finish transcribing notes. +1996-09-19 : CMSMcQ : begin transcribing notes for draft. +1996-09-13 : CMSMcQ : made outline from notes of 09-06, +do some housekeeping + + +

+ + +Introduction +

Extensible Markup Language, abbreviated XML, describes a class of +data objects called XML documents and +partially describes the behavior of +computer programs which process them. XML is an application profile or +restricted form of SGML, the Standard Generalized Markup +Language . +By construction, XML documents +are conforming SGML documents. +

XML documents are made up of storage units called entities, which contain either parsed +or unparsed data. +Parsed data is made up of characters, +some +of which form character data, +and some of which form markup. +Markup encodes a description of the document's storage layout and +logical structure. XML provides a mechanism to impose constraints on +the storage layout and logical structure.

A software module +called an XML processor is used to read XML documents +and provide access to their content and structure. It is assumed that an XML processor is +doing its work on behalf of another module, called the +application. This specification describes the +required behavior of an XML processor in terms of how it must read XML +data and the information it must provide to the application.

+ + +Origin and Goals +

XML was developed by an XML Working Group (originally known as the +SGML Editorial Review Board) formed under the auspices of the World +Wide Web Consortium (W3C) in 1996. +It was chaired by Jon Bosak of Sun +Microsystems with the active participation of an XML Special +Interest Group (previously known as the SGML Working Group) also +organized by the W3C. The membership of the XML Working Group is given +in an appendix. Dan Connolly served as the WG's contact with the W3C. +

The design goals for XML are: +

XML shall be straightforwardly usable over the +Internet.

XML shall support a wide variety of applications.

XML shall be compatible with SGML.

It shall be easy to write programs which process XML +documents.

The number of optional features in XML is to be kept to the +absolute minimum, ideally zero.

XML documents should be human-legible and reasonably +clear.

The XML design should be prepared quickly.

The design of XML shall be formal and concise.

XML documents shall be easy to create.

Terseness in XML markup is of minimal importance.

This specification, +together with associated standards +(Unicode and ISO/IEC 10646 for characters, +Internet RFC 1766 for language identification tags, +ISO 639 for language name codes, and +ISO 3166 for country name codes), +provides all the information necessary to understand +XML Version &XML.version; +and construct computer programs to process it.

This version of the XML specification + +&doc.distribution;.

+ + + + + + + +Terminology + +

The terminology used to describe XML documents is defined in the body of +this specification. +The terms defined in the following list are used in building those +definitions and in describing the actions of an XML processor: + + +may +

Conforming documents and XML +processors are permitted to but need not behave as +described.

+ + +must +

Conforming documents and XML processors +are required to behave as described; otherwise they are in error. + +

+ + +error +

A violation of the rules of this +specification; results are +undefined. Conforming software may detect and report an error and may +recover from it.

+ + +fatal error +

An error +which a conforming XML processor +must detect and report to the application. +After encountering a fatal error, the +processor may continue +processing the data to search for further errors and may report such +errors to the application. In order to support correction of errors, +the processor may make unprocessed data from the document (with +intermingled character data and markup) available to the application. +Once a fatal error is detected, however, the processor must not +continue normal processing (i.e., it must not +continue to pass character data and information about the document's +logical structure to the application in the normal way). +

+ + +at user option +

Conforming software may or must (depending on the modal verb in the +sentence) behave as described; if it does, it must +provide users a means to enable or disable the behavior +described.

+ + +validity constraint +

A rule which applies to all +valid XML documents. +Violations of validity constraints are errors; they must, at user option, +be reported by +validating XML processors.

+ + +well-formedness constraint +

A rule which applies to all well-formed XML documents. +Violations of well-formedness constraints are +fatal errors.

+ + + +match +

(Of strings or names:) +Two strings or names being compared must be identical. +Characters with multiple possible representations in ISO/IEC 10646 (e.g. +characters with +both precomposed and base+diacritic forms) match only if they have the +same representation in both strings. +At user option, processors may normalize such characters to +some canonical form. +No case folding is performed. +(Of strings and rules in the grammar:) +A string matches a grammatical production if it belongs to the +language generated by that production. +(Of content and content models:) +An element matches its declaration when it conforms +in the fashion described in the constraint +. + +

+ + +for compatibility +

A feature of +XML included solely to ensure that XML remains compatible with SGML. +

+ + +for interoperability +

A +non-binding recommendation included to increase the chances that XML +documents can be processed by the existing installed base of SGML +processors which predate the +&WebSGML;.

+ + +

+ + + + + + + +Documents + +

+A data object is an +XML document if it is +well-formed, as +defined in this specification. +A well-formed XML document may in addition be +valid if it meets certain further +constraints.

+ +

Each XML document has both a logical and a physical structure. +Physically, the document is composed of units called entities. An entity may refer to other entities to cause their +inclusion in the document. A document begins in a "root" or document entity. +Logically, the document is composed of declarations, elements, +comments, +character references, and +processing +instructions, all of which are indicated in the document by explicit +markup. +The logical and physical structures must nest properly, as described +in . +

+ + +Well-Formed XML Documents + +

+A textual object is +a well-formed XML document if: + +

Taken as a whole, it +matches the production labeled document.

It +meets all the well-formedness constraints given in this specification.

+ +

Each of the parsed entities +which is referenced directly or indirectly within the document is +well-formed.

+ +Document +document +prolog +element +Misc* + +

Matching the document production +implies that: + +

It contains one or more +elements.

+ + +

There is exactly +one element, called the root, or document element, no +part of which appears in the content of any other element. +For all other elements, if the start-tag is in the content of another +element, the end-tag is in the content of the same element. More +simply stated, the elements, delimited by start- and end-tags, nest +properly within each other. +

+ +

As a consequence +of this, +for each non-root element +C in the document, there is one other element P +in the document such that +C is in the content of P, but is not in +the content of any other element that is in the content of +P. +P is referred to as the +parent of C, and C as a +child of P.

+ + +Characters + +

A parsed entity contains +text, a sequence of +characters, +which may represent markup or character data. +A character +is an atomic unit of text as specified by +ISO/IEC 10646 . +Legal characters are tab, carriage return, line feed, and the legal +graphic characters of Unicode and ISO/IEC 10646. +The use of "compatibility characters", as defined in section 6.8 +of , is discouraged. + + +Character Range + +Char +#x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] +| [#x10000-#x10FFFF] +any Unicode character, excluding the +surrogate blocks, FFFE, and FFFF. + + +

+ +

The mechanism for encoding character code points into bit patterns may +vary from entity to entity. All XML processors must accept the UTF-8 +and UTF-16 encodings of 10646; the mechanisms for signaling which of +the two is in use, or for bringing other encodings into play, are +discussed later, in . +

+ + + + +Common Syntactic Constructs + +

This section defines some symbols used widely in the grammar.

S (white space) consists of one or more space (#x20) +characters, carriage returns, line feeds, or tabs. + + +White Space + +S +(#x20 | #x9 | #xD | #xA)+ + + +

Characters are classified for convenience as letters, digits, or other +characters. Letters consist of an alphabetic or syllabic +base character possibly +followed by one or more combining characters, or of an ideographic +character. +Full definitions of the specific characters in each class +are given in .

A Name is a token +beginning with a letter or one of a few punctuation characters, and continuing +with letters, digits, hyphens, underscores, colons, or full stops, together +known as name characters. +Names beginning with the string "xml", or any string +which would match (('X'|'x') ('M'|'m') ('L'|'l')), are +reserved for standardization in this or future versions of this +specification. +

+ +

The colon character within XML names is reserved for experimentation with +name spaces. +Its meaning is expected to be +standardized at some future point, at which point those documents +using the colon for experimental purposes may need to be updated. +(There is no guarantee that any name-space mechanism +adopted for XML will in fact use the colon as a name-space delimiter.) +In practice, this means that authors should not use the colon in XML +names except as part of name-space experiments, but that XML processors +should accept the colon as a name character.

+ +

An +Nmtoken (name token) is any mixture of +name characters. + +Names and Tokens +NameChar +Letter +| Digit +| '.' | '-' | '_' | ':' +| CombiningChar +| Extender + +Name +(Letter | '_' | ':') +(NameChar)* +Names +Name +(S Name)* +Nmtoken +(NameChar)+ +Nmtokens +Nmtoken (S Nmtoken)* + +

Literal data is any quoted string not containing +the quotation mark used as a delimiter for that string. +Literals are used +for specifying the content of internal entities +(EntityValue), +the values of attributes (AttValue), +and external identifiers +(SystemLiteral). +Note that a SystemLiteral +can be parsed without scanning for markup. + +Literals +EntityValue +'"' +([^%&"] +| PEReference +| Reference)* +'"' + +| +"'" +([^%&'] +| PEReference +| Reference)* +"'" + +AttValue +'"' +([^<&"] +| Reference)* +'"' + +| +"'" +([^<&'] +| Reference)* +"'" + +SystemLiteral +('"' [^"]* '"') | ("'" [^']* "'") + + +PubidLiteral +'"' PubidChar* +'"' +| "'" (PubidChar - "'")* "'" + +PubidChar +#x20 | #xD | #xA +| [a-zA-Z0-9] +| [-'()+,./:=?;!*#@$_%] + + +

+ + + + +Character Data and Markup + +

Text consists of intermingled +character +data and markup. +Markup takes the form of +start-tags, +end-tags, +empty-element tags, +entity references, +character references, +comments, +CDATA section delimiters, +document type declarations, and +processing instructions. + +

All text that is not markup +constitutes the character data of +the document.

The ampersand character (&) and the left angle bracket (<) +may appear in their literal form only when used as markup +delimiters, or within a comment, a +processing instruction, +or a CDATA section. + +They are also legal within the literal entity +value of an internal entity declaration; see +. + +If they are needed elsewhere, +they must be escaped +using either numeric character references +or the strings +"&" and "<" respectively. +The right angle +bracket (>) may be represented using the string +">", and must, for +compatibility, +be escaped using +">" or a character reference +when it appears in the string +"]]>" +in content, +when that string is not marking the end of +a CDATA section. +

+In the content of elements, character data +is any string of characters which does +not contain the start-delimiter of any markup. +In a CDATA section, character data +is any string of characters not including the CDATA-section-close +delimiter, "]]>".

+To allow attribute values to contain both single and double quotes, the +apostrophe or single-quote character (') may be represented as +"'", and the double-quote character (") as +""". + +Character Data + +CharData +[^<&]* - ([^<&]* ']]>' [^<&]*) + + +

+ + + +Comments + +

Comments may +appear anywhere in a document outside other +markup; in addition, +they may appear within the document type declaration +at places allowed by the grammar. +They are not part of the document's character +data; an XML +processor may, but need not, make it possible for an application to +retrieve the text of comments. +For compatibility, the string +"--" (double-hyphen) must not occur within +comments. + +Comments +Comment +'' + + +

An example of a comment: +<!&como; declarations for <head> & <body> &comc;> +

+ + + +Processing Instructions + +

Processing +instructions (PIs) allow documents to contain instructions +for applications. + + +Processing Instructions +PI +'<?' PITarget +(S +(Char* - +(Char* &pic; Char*)))? +&pic; +PITarget +Name - +(('X' | 'x') ('M' | 'm') ('L' | 'l')) + + +PIs are not part of the document's character +data, but must be passed through to the application. The +PI begins with a target (PITarget) used +to identify the application to which the instruction is directed. +The target names "XML", "xml", and so on are +reserved for standardization in this or future versions of this +specification. +The +XML Notation mechanism +may be used for +formal declaration of PI targets. +

+ + + +CDATA Sections + +

CDATA sections +may occur +anywhere character data may occur; they are +used to escape blocks of text containing characters which would +otherwise be recognized as markup. CDATA sections begin with the +string "<![CDATA[" and end with the string +"]]>": + +CDATA Sections +CDSect +CDStart +CData +CDEnd +CDStart +'<![CDATA[' + +CData +(Char* - +(Char* ']]>' Char*)) + + +CDEnd +']]>' + + + +Within a CDATA section, only the CDEnd string is +recognized as markup, so that left angle brackets and ampersands may occur in +their literal form; they need not (and cannot) be escaped using +"<" and "&". CDATA sections +cannot nest. +

+ +

An example of a CDATA section, in which "<greeting>" and +"</greeting>" +are recognized as character data, not +markup: +<![CDATA[<greeting>Hello, world!</greeting>]]> +

+ + + +Prolog and Document Type Declaration + +

XML documents +may, and should, +begin with an XML declaration which specifies +the version of +XML being used. +For example, the following is a complete XML document, well-formed but not +valid: + +Hello, world! +]]> +and so is this: +Hello, world! +]]> +

+ +

The version number "1.0" should be used to indicate +conformance to this version of this specification; it is an error +for a document to use the value "1.0" +if it does not conform to this version of this specification. +It is the intent +of the XML working group to give later versions of this specification +numbers other than "1.0", but this intent does not +indicate a +commitment to produce any future versions of XML, nor if any are produced, to +use any particular numbering scheme. +Since future versions are not ruled out, this construct is provided +as a means to allow the possibility of automatic version recognition, should +it become necessary. +Processors may signal an error if they receive documents labeled with +versions they do not support. +

The function of the markup in an XML document is to describe its +storage and logical structure and to associate attribute-value pairs +with its logical structures. XML provides a mechanism, the document type declaration, to define +constraints on the logical structure and to support the use of +predefined storage units. + +An XML document is +valid if it has an associated document type +declaration and if the document +complies with the constraints expressed in it.

The document type declaration must appear before +the first element in the document. + +Prolog + +prolog +XMLDecl? +Misc* +(doctypedecl +Misc*)? +XMLDecl +&xmlpio; +VersionInfo +EncodingDecl? +SDDecl? +S? +&pic; + +VersionInfo +S 'version' Eq +(' VersionNum ' +| " VersionNum ") + +Eq +S? '=' S? + +VersionNum +([a-zA-Z0-9_.:] | '-')+ + +Misc +Comment | PI | +S + +

+ +

The XML +document type declaration +contains or points to +markup declarations +that provide a grammar for a +class of documents. +This grammar is known as a document type definition, +or DTD. +The document type declaration can point to an external subset (a +special kind of +external entity) containing markup +declarations, or can +contain the markup declarations directly in an internal subset, or can do +both. +The DTD for a document consists of both subsets taken +together. +

+A markup declaration is +an element type declaration, +an attribute-list declaration, +an entity declaration, or +a notation declaration. + +These declarations may be contained in whole or in part +within parameter entities, +as described in the well-formedness and validity constraints below. +For fuller information, see +.

The markup declarations may be made up in whole or in part of +the replacement text of +parameter entities. +The productions later in this specification for +individual nonterminals (elementdecl, +AttlistDecl, and so on) describe +the declarations after all the parameter entities have been +included.

+ + +Root Element Type +

+The Name in the document type declaration must +match the element type of the root element. +

+ + + +Proper Declaration/PE Nesting +

Parameter-entity +replacement text must be properly nested +with markup declarations. +That is to say, if either the first character +or the last character of a markup +declaration (markupdecl above) +is contained in the replacement text for a +parameter-entity reference, +both must be contained in the same replacement text.

+ + +PEs in Internal Subset +

In the internal DTD subset, +parameter-entity references +can occur only where markup declarations can occur, not +within markup declarations. (This does not apply to +references that occur in +external parameter entities or to the external subset.) +

+ +

+Like the internal subset, the external subset and +any external parameter entities referred to in the DTD +must consist of a series of complete markup declarations of the types +allowed by the non-terminal symbol +markupdecl, interspersed with white space +or parameter-entity references. +However, portions of the contents +of the +external subset or of external parameter entities may conditionally be ignored +by using +the conditional section +construct; this is not allowed in the internal subset. + + +External Subset + +extSubset +TextDecl? +extSubsetDecl +extSubsetDecl +( +markupdecl +| conditionalSect +| PEReference +| S +)* + + +

The external subset and external parameter entities also differ +from the internal subset in that in them, +parameter-entity references +are permitted within markup declarations, +not only between markup declarations.

An example of an XML document with a document type declaration: + + +Hello, world! +]]> +The system identifier +"hello.dtd" gives the URI of a DTD for the document.

The declarations can also be given locally, as in this +example: + + +]> +Hello, world! +]]> +If both the external and internal subsets are used, the +internal subset is considered to occur before the external subset. + +This has the effect that entity and attribute-list declarations in the +internal subset take precedence over those in the external subset. +

+ + + +Standalone Document Declaration +

Markup declarations can affect the content of the document, +as passed from an XML processor +to an application; examples are attribute defaults and entity +declarations. +The standalone document declaration, +which may appear as a component of the XML declaration, signals +whether or not there are such declarations which appear external to +the document entity. + +Standalone Document Declaration + +SDDecl + +S +'standalone' Eq +(("'" ('yes' | 'no') "'") | ('"' ('yes' | 'no') '"')) + + + +

+In a standalone document declaration, the value "yes" indicates +that there +are no markup declarations external to the document +entity (either in the DTD external subset, or in an +external parameter entity referenced from the internal subset) +which affect the information passed from the XML processor to +the application. +The value "no" indicates that there are or may be such +external markup declarations. +Note that the standalone document declaration only +denotes the presence of external declarations; the presence, in a +document, of +references to external entities, when those entities are +internally declared, +does not change its standalone status.

If there are no external markup declarations, the standalone document +declaration has no meaning. +If there are external markup declarations but there is no standalone +document declaration, the value "no" is assumed.

Any XML document for which standalone="no" holds can +be converted algorithmically to a standalone document, +which may be desirable for some network delivery applications.

+ +Standalone Document Declaration +

The standalone document declaration must have +the value "no" if any external markup declarations +contain declarations of:

attributes with default values, if +elements to which +these attributes apply appear in the document without +specifications of values for these attributes, or

entities (other than &magicents;), +if references to those +entities appear in the document, or

+ +

attributes with values subject to +normalization, where the +attribute appears in the document with a value which will +change as a result of normalization, or

+ + +

element types with element content, +if white space occurs +directly within any instance of those types. +

+ + + +

An example XML declaration with a standalone document declaration:<?xml version="&XML.version;" standalone='yes'?>

+ + +White Space Handling + +

In editing XML documents, it is often convenient to use "white space" +(spaces, tabs, and blank lines, denoted by the nonterminal +S in this specification) to +set apart the markup for greater readability. Such white space is typically +not intended for inclusion in the delivered version of the document. +On the other hand, "significant" white space that should be preserved in the +delivered version is common, for example in poetry and +source code.

An XML processor +must always pass all characters in a document that are not +markup through to the application. A +validating XML processor must also inform the application +which of these characters constitute white space appearing +in element content. +

A special attribute +named xml:space may be attached to an element +to signal an intention that in that element, +white space should be preserved by applications. +In valid documents, this attribute, like any other, must be +declared if it is used. +When declared, it must be given as an +enumerated type whose only +possible values are "default" and "preserve". +For example:]]>

The value "default" signals that applications' +default white-space processing modes are acceptable for this element; the +value "preserve" indicates the intent that applications preserve +all the white space. +This declared intent is considered to apply to all elements within the content +of the element where it is specified, unless overriden with another instance +of the xml:space attribute. +

The root element of any document +is considered to have signaled no intentions as regards application space +handling, unless it provides a value for +this attribute or the attribute is declared with a default value. +

+ + + +End-of-Line Handling +

XML parsed entities are often stored in +computer files which, for editing convenience, are organized into lines. +These lines are typically separated by some combination of the characters +carriage-return (#xD) and line-feed (#xA).

To simplify the tasks of applications, +wherever an external parsed entity or the literal entity value +of an internal parsed entity contains either the literal +two-character sequence "#xD#xA" or a standalone literal +#xD, an XML processor must +pass to the application the single character #xA. +(This behavior can +conveniently be produced by normalizing all +line breaks to #xA on input, before parsing.) +

+ + +Language Identification +

In document processing, it is often useful to +identify the natural or formal language +in which the content is +written. +A special attribute named +xml:lang may be inserted in +documents to specify the +language used in the contents and attribute values +of any element in an XML document. +In valid documents, this attribute, like any other, must be +declared if it is used. +The values of the attribute are language identifiers as defined +by , "Tags for the Identification of Languages": + +Language Identification +LanguageID +Langcode +('-' Subcode)* +Langcode +ISO639Code | +IanaCode | +UserCode + +ISO639Code +([a-z] | [A-Z]) ([a-z] | [A-Z]) +IanaCode +('i' | 'I') '-' ([a-z] | [A-Z])+ +UserCode +('x' | 'X') '-' ([a-z] | [A-Z])+ +Subcode +([a-z] | [A-Z])+ + +The Langcode may be any of the following: + +

a two-letter language code as defined by +, "Codes +for the representation of names of languages"

a language identifier registered with the Internet +Assigned Numbers Authority ; these begin with the +prefix "i-" (or "I-")

a language identifier assigned by the user, or agreed on +between parties in private use; these must begin with the +prefix "x-" or "X-" in order to ensure that they do not conflict +with names later standardized or registered with IANA

There may be any number of Subcode segments; if +the first +subcode segment exists and the Subcode consists of two +letters, then it must be a country code from +, "Codes +for the representation of names of countries." +If the first +subcode consists of more than two letters, it must be +a subcode for the language in question registered with IANA, +unless the Langcode begins with the prefix +"x-" or +"X-".

It is customary to give the language code in lower case, and +the country code (if any) in upper case. +Note that these values, unlike other names in XML documents, +are case insensitive.

For example: +The quick brown fox jumps over the lazy dog.

What colour is it?

What color is it?

+ + Habe nun, ach! Philosophie, + Juristerei, und Medizin + und leider auch Theologie + durchaus studiert mit heißem Bemüh'n. + ]]>

+ +

The intent declared with xml:lang is considered to apply to +all attributes and content of the element where it is specified, +unless overridden with an instance of xml:lang +on another element within that content.

+ +

A simple declaration for xml:lang might take +the form +xml:lang NMTOKEN #IMPLIED +but specific default values may also be given, if appropriate. In a +collection of French poems for English students, with glosses and +notes in English, the xml:lang attribute might be declared this way: + + + ]]> +

+ + + + + + +Logical Structures + +

Each XML document contains one or more +elements, the boundaries of which are +either delimited by start-tags +and end-tags, or, for empty elements, by an empty-element tag. Each element has a type, +identified by name, sometimes called its "generic +identifier" (GI), and may have a set of +attribute specifications. Each attribute specification +has a name and a value. +

+Element +element +EmptyElemTag +| STag content +ETag + + + + +

This specification does not constrain the semantics, use, or (beyond +syntax) names of the element types and attributes, except that names +beginning with a match to (('X'|'x')('M'|'m')('L'|'l')) +are reserved for standardization in this or future versions of this +specification. +

+ +Element Type Match +

+The Name in an element's end-tag must match +the element type in +the start-tag. +

+ + +Element Valid +

An element is +valid if +there is a declaration matching +elementdecl where the +Name matches the element type, and +one of the following holds:

+ +

The declaration matches EMPTY and the element has no +content.

The declaration matches children and +the sequence of +child elements +belongs to the language generated by the regular expression in +the content model, with optional white space (characters +matching the nonterminal S) between each pair +of child elements.

The declaration matches Mixed and +the content consists of character +data and child elements +whose types match names in the content model.

The declaration matches ANY, and the types +of any child elements have +been declared.

+ + + + +Start-Tags, End-Tags, and Empty-Element Tags + +

The beginning of every +non-empty XML element is marked by a start-tag. + +Start-tag + +STag +'<' Name +(S Attribute)* +S? '>' + + +Attribute +Name Eq +AttValue + + + + + +The Name in +the start- and end-tags gives the +element's type. + +The Name-AttValue pairs are +referred to as +the attribute specifications of the element, +with the +Name in each pair +referred to as the attribute name and +the content of the +AttValue (the text between the +' or " delimiters) +as the attribute value. +

+ +Unique Att Spec +

+No attribute name may appear more than once in the same start-tag +or empty-element tag. +

+ + +Attribute Value Type +

+The attribute must have been declared; the value must be of the type +declared for it. +(For attribute types, see .) +

+ + +No External Entity References +

+Attribute values cannot contain direct or indirect entity references +to external entities. +

+ + +No < in Attribute Values +

The replacement text of any entity +referred to directly or indirectly in an attribute +value (other than "<") must not contain +a <. +

An example of a start-tag: +<termdef id="dt-dog" term="dog">

The end of every element +that begins with a start-tag must +be marked by an end-tag +containing a name that echoes the element's type as given in the +start-tag: + +End-tag + +ETag +'</' Name +S? '>' + + +

An example of an end-tag:</termdef>

If an element is empty, +it must be represented either by a start-tag immediately followed +by an end-tag or by an empty-element tag. +An +empty-element tag takes a special form: + +Tags for Empty Elements + +EmptyElemTag +'<' Name (S +Attribute)* S? +'/>' + + + + +

Empty-element tags may be used for any element which has no +content, whether or not it is declared using the keyword +EMPTY. +For interoperability, the empty-element +tag must be used, and can only be used, for elements which are +declared EMPTY.

Examples of empty elements: +<IMG align="left" + src="http://www.w3.org/Icons/WWW/w3c_home" /> +<br></br> +<br/>

+ + + +Element Type Declarations + +

The element structure of an +XML document may, for +validation purposes, +be constrained +using element type and attribute-list declarations. +An element type declaration constrains the element's +content. +

+ +

Element type declarations often constrain which element types can +appear as children of the element. +At user option, an XML processor may issue a warning +when a declaration mentions an element type for which no declaration +is provided, but this is not an error.

An element +type declaration takes the form: + +Element Type Declaration + +elementdecl +'<!ELEMENT' S +Name +S +contentspec +S? '>' + +contentspec +'EMPTY' +| 'ANY' +| Mixed +| children + + + + +where the Name gives the element type +being declared. +

+ + +Unique Element Type Declaration +

+No element type may be declared more than once. +

+ + +

Examples of element type declarations: +<!ELEMENT br EMPTY> +<!ELEMENT p (#PCDATA|emph)* > +<!ELEMENT %name.para; %content.para; > +<!ELEMENT container ANY>

+ + +Element Content + +

An element type has +element content when elements of that +type must contain only child +elements (no character data), optionally separated by +white space (characters matching the nonterminal +S). + +In this case, the +constraint includes a content model, a simple grammar governing +the allowed types of the child +elements and the order in which they are allowed to appear. +The grammar is built on +content particles (cps), which consist of names, +choice lists of content particles, or +sequence lists of content particles: + +Element-content Models + +children +(choice +| seq) +('?' | '*' | '+')? +cp +(Name +| choice +| seq) +('?' | '*' | '+')? +choice +'(' S? cp +( S? '|' S? cp )* +S? ')' + +seq +'(' S? cp +( S? ',' S? cp )* +S? ')' + + + + +where each Name is the type of an element which may +appear as a child. +Any content +particle in a choice list may appear in the element content at the location where +the choice list appears in the grammar; +content particles occurring in a sequence list must each +appear in the element content in the +order given in the list. +The optional character following a name or list governs +whether the element or the content particles in the list may occur one +or more (+), zero or more (*), or zero or +one times (?). +The absence of such an operator means that the element or content particle +must appear exactly once. +This syntax +and meaning are identical to those used in the productions in this +specification.

+The content of an element matches a content model if and only if it is +possible to trace out a path through the content model, obeying the +sequence, choice, and repetition operators and matching each element in +the content against an element type in the content model. For compatibility, it is an error +if an element in the document can +match more than one occurrence of an element type in the content model. +For more information, see . + + +

+ +Proper Group/PE Nesting +

Parameter-entity +replacement text must be properly nested +with parenthetized groups. +That is to say, if either of the opening or closing parentheses +in a choice, seq, or +Mixed construct +is contained in the replacement text for a +parameter entity, +both must be contained in the same replacement text.

For interoperability, +if a parameter-entity reference appears in a +choice, seq, or +Mixed construct, its replacement text +should not be empty, and +neither the first nor last non-blank +character of the replacement text should be a connector +(| or ,). +

+ +

Examples of element-content models: +<!ELEMENT spec (front, body, back?)> +<!ELEMENT div1 (head, (p | list | note)*, div2*)> +<!ELEMENT dictionary-body (%div.mix; | %dict.mix;)*>

+ + + +Mixed Content + +

An element +type has +mixed content when elements of that type may contain +character data, optionally interspersed with +child elements. +In this case, the types of the child elements +may be constrained, but not their order or their number of occurrences: + +Mixed-content Declaration + +Mixed +'(' S? +'#PCDATA' +(S? +'|' +S? +Name)* +S? +')*' +| '(' S? '#PCDATA' S? ')' + + + + + + +where the Names give the types of elements +that may appear as children. +

+ +No Duplicate Types +

The same name must not appear more than once in a single mixed-content +declaration. +

+ + + + +Attribute-List Declarations + +

Attributes are used to associate +name-value pairs with elements. +Attribute specifications may appear only within start-tags +and empty-element tags; +thus, the productions used to +recognize them appear in . +Attribute-list +declarations may be used: + +

To define the set of attributes pertaining to a given +element type.

To establish type constraints for these +attributes.

To provide default values +for attributes.

+ +

+Attribute-list declarations specify the name, data type, and default +value (if any) of each attribute associated with a given element type: + +Attribute-list Declaration +AttlistDecl +'<!ATTLIST' S +Name +AttDef* +S? '>' + +AttDef +S Name +S AttType +S DefaultDecl + + +The Name in the +AttlistDecl rule is the type of an element. At +user option, an XML processor may issue a warning if attributes are +declared for an element type not itself declared, but this is not an +error. The Name in the +AttDef rule is +the name of the attribute.

+When more than one AttlistDecl is provided for a +given element type, the contents of all those provided are merged. When +more than one definition is provided for the same attribute of a +given element type, the first declaration is binding and later +declarations are ignored. +For interoperability, writers of DTDs +may choose to provide at most one attribute-list declaration +for a given element type, at most one attribute definition +for a given attribute name, and at least one attribute definition +in each attribute-list declaration. +For interoperability, an XML processor may at user option +issue a warning when more than one attribute-list declaration is +provided for a given element type, or more than one attribute definition +is provided +for a given attribute, but this is not an error. +

+ + +Attribute Types + +

XML attribute types are of three kinds: a string type, a +set of tokenized types, and enumerated types. The string type may take +any literal string as a value; the tokenized types have varying lexical +and semantic constraints, as noted: + +Attribute Types + +AttType +StringType +| TokenizedType +| EnumeratedType + + +StringType +'CDATA' + +TokenizedType +'ID' + + + +| 'IDREF' + +| 'IDREFS' + +| 'ENTITY' + +| 'ENTITIES' + +| 'NMTOKEN' + +| 'NMTOKENS' + + + +

+ +ID +

+Values of type ID must match the +Name production. +A name must not appear more than once in +an XML document as a value of this type; i.e., ID values must uniquely +identify the elements which bear them. +

+ + +One ID per Element Type +

No element type may have more than one ID attribute specified.

+ + +ID Attribute Default +

An ID attribute must have a declared default of #IMPLIED or +#REQUIRED.

+ + +IDREF +

+Values of type IDREF must match +the Name production, and +values of type IDREFS must match +Names; +each Name must match the value of an ID attribute on +some element in the XML document; i.e. IDREF values must +match the value of some ID attribute. +

+ + +Entity Name +

+Values of type ENTITY +must match the Name production, +values of type ENTITIES must match +Names; +each Name must +match the +name of an unparsed entity declared in the +DTD. +

+ + +Name Token +

+Values of type NMTOKEN must match the +Nmtoken production; +values of type NMTOKENS must +match Nmtokens. +

+ + +

Enumerated attributes can take one +of a list of values provided in the declaration. There are two +kinds of enumerated types: + +Enumerated Attribute Types +EnumeratedType +NotationType +| Enumeration + +NotationType +'NOTATION' +S +'(' +S? +Name +(S? '|' S? +Name)* +S? ')' + + +Enumeration +'(' S? +Nmtoken +(S? '|' +S? +Nmtoken)* +S? +')' + + +A NOTATION attribute identifies a +notation, declared in the +DTD with associated system and/or public identifiers, to +be used in interpreting the element to which the attribute +is attached. +

+ + +Notation Attributes +

+Values of this type must match +one of the notation names included in +the declaration; all notation names in the declaration must +be declared. +

+ + +Enumeration +

+Values of this type +must match one of the Nmtoken tokens in the +declaration. +

+ +

For interoperability, the same +Nmtoken should not occur more than once in the +enumerated attribute types of a single element type. +

+ + + +Attribute Defaults + +

An attribute declaration provides +information on whether +the attribute's presence is required, and if not, how an XML processor should +react if a declared attribute is absent in a document. + +Attribute Defaults + +DefaultDecl +'#REQUIRED' +| '#IMPLIED' +| (('#FIXED' S)? AttValue) + + + + + + + + +

In an attribute declaration, #REQUIRED means that the +attribute must always be provided, #IMPLIED that no default +value is provided. + +If the +declaration +is neither #REQUIRED nor #IMPLIED, then the +AttValue value contains the declared +default value; the #FIXED keyword states that +the attribute must always have the default value. +If a default value +is declared, when an XML processor encounters an omitted attribute, it +is to behave as though the attribute were present with +the declared default value.

+ +Required Attribute +

If the default declaration is the keyword #REQUIRED, then +the attribute must be specified for +all elements of the type in the attribute-list declaration. +

+ +Attribute Default Legal +

+The declared +default value must meet the lexical constraints of the declared attribute type. +

+ + +Fixed Attribute Default +

If an attribute has a default value declared with the +#FIXED keyword, instances of that attribute must +match the default value. +

+ +

Examples of attribute-list declarations: +<!ATTLIST termdef + id ID #REQUIRED + name CDATA #IMPLIED> +<!ATTLIST list + type (bullets|ordered|glossary) "ordered"> +<!ATTLIST form + method CDATA #FIXED "POST">

+ + +Attribute-Value Normalization +

Before the value of an attribute is passed to the application +or checked for validity, the +XML processor must normalize it as follows: + +

a character reference is processed by appending the referenced +character to the attribute value

an entity reference is processed by recursively processing the +replacement text of the entity

a whitespace character (#x20, #xD, #xA, #x9) is processed by +appending #x20 to the normalized value, except that only a single #x20 +is appended for a "#xD#xA" sequence that is part of an external +parsed entity or the literal entity value of an internal parsed +entity

other characters are processed by appending them to the normalized +value

+ +

If the declared value is not CDATA, then the XML processor must +further process the normalized attribute value by discarding any +leading and trailing space (#x20) characters, and by replacing +sequences of space (#x20) characters by a single space (#x20) +character.

+All attributes for which no declaration has been read should be treated +by a non-validating parser as if declared +CDATA. +

+ + + +Conditional Sections +

+Conditional sections are portions of the +document type declaration external subset +which are +included in, or excluded from, the logical structure of the DTD based on +the keyword which governs them. + +Conditional Section + +conditionalSect +includeSect +| ignoreSect + + +includeSect +'<![' S? 'INCLUDE' S? '[' + +extSubsetDecl +']]>' + + +ignoreSect +'<![' S? 'IGNORE' S? '[' +ignoreSectContents* +']]>' + + +ignoreSectContents +Ignore +('<![' ignoreSectContents ']]>' +Ignore)* +Ignore +Char* - +(Char* ('<![' | ']]>') +Char*) + + + + +

Like the internal and external DTD subsets, a conditional section +may contain one or more complete declarations, +comments, processing instructions, +or nested conditional sections, intermingled with white space. +

If the keyword of the +conditional section is INCLUDE, then the contents of the conditional +section are part of the DTD. +If the keyword of the conditional +section is IGNORE, then the contents of the conditional section are +not logically part of the DTD. +Note that for reliable parsing, the contents of even ignored +conditional sections must be read in order to +detect nested conditional sections and ensure that the end of the +outermost (ignored) conditional section is properly detected. +If a conditional section with a +keyword of INCLUDE occurs within a larger conditional +section with a keyword of IGNORE, both the outer and the +inner conditional sections are ignored.

If the keyword of the conditional section is a +parameter-entity reference, the parameter entity must be replaced by its +content before the processor decides whether to +include or ignore the conditional section.

An example: +<!ENTITY % draft 'INCLUDE' > +<!ENTITY % final 'IGNORE' > + +<![%draft;[ +<!ELEMENT book (comments*, title, body, supplements?)> +]]> +<![%final;[ +<!ELEMENT book (title, body, supplements?)> +]]> + +

+ + + + + + + + + +Physical Structures + +

An XML document may consist +of one or many storage units. These are called +entities; they all have content and are all +(except for the document entity, see below, and +the external DTD subset) +identified by name. + +Each XML document has one entity +called the document entity, which serves +as the starting point for the XML +processor and may contain the whole document.

Entities may be either parsed or unparsed. +A parsed entity's +contents are referred to as its +replacement text; +this text is considered an +integral part of the document.

+ +

An +unparsed entity +is a resource whose contents may or may not be +text, and if text, may not be XML. +Each unparsed entity +has an associated notation, identified by name. +Beyond a requirement +that an XML processor make the identifiers for the entity and +notation available to the application, +XML places no constraints on the contents of unparsed entities. +

+Parsed entities are invoked by name using entity references; +unparsed entities by name, given in the value of ENTITY +or ENTITIES +attributes.

General entities +are entities for use within the document content. +In this specification, general entities are sometimes referred +to with the unqualified term entity when this leads +to no ambiguity. +Parameter entities +are parsed entities for use within the DTD. +These two types of entities use different forms of reference and +are recognized in different contexts. +Furthermore, they occupy different namespaces; a parameter entity and +a general entity with the same name are two distinct entities. +

+ + +Character and Entity References +

+A character reference refers to a specific character in the +ISO/IEC 10646 character set, for example one not directly accessible from +available input devices. + +Character Reference +CharRef +'&#' [0-9]+ ';' +| '&hcro;' [0-9a-fA-F]+ ';' + + + + +Legal Character +

Characters referred to using character references must +match the production for +Char.

+ +If the character reference begins with "&#x", the digits and +letters up to the terminating ; provide a hexadecimal +representation of the character's code point in ISO/IEC 10646. +If it begins just with "&#", the digits up to the terminating +; provide a decimal representation of the character's +code point. + +

An entity +reference refers to the content of a named entity. +References to +parsed general entities +use ampersand (&) and semicolon (;) as +delimiters. + +Parameter-entity references use percent-sign (%) and +semicolon +(;) as delimiters. +

+ +Entity Reference +Reference +EntityRef +| CharRef +EntityRef +'&' Name ';' + + + + + +PEReference +'%' Name ';' + + + + + + + +Entity Declared +

In a document without any DTD, a document with only an internal +DTD subset which contains no parameter entity references, or a document with +"standalone='yes'", +the Name given in the entity reference must +match that in an +entity declaration, except that +well-formed documents need not declare +any of the following entities: &magicents;. +The declaration of a parameter entity must precede any reference to it. +Similarly, the declaration of a general entity must precede any +reference to it which appears in a default value in an attribute-list +declaration.

Note that if entities are declared in the external subset or in +external parameter entities, a non-validating processor is +not obligated to read +and process their declarations; for such documents, the rule that +an entity must be declared is a well-formedness constraint only +if standalone='yes'.

+ + +Entity Declared +

In a document with an external subset or external parameter +entities with "standalone='no'", +the Name given in the entity reference must match that in an +entity declaration. +For interoperability, valid documents should declare the entities +&magicents;, in the form +specified in . +The declaration of a parameter entity must precede any reference to it. +Similarly, the declaration of a general entity must precede any +reference to it which appears in a default value in an attribute-list +declaration.

+ + + +Parsed Entity +

+An entity reference must not contain the name of an unparsed entity. Unparsed entities may be referred +to only in attribute values declared to +be of type ENTITY or ENTITIES. +

+ + +No Recursion +

+A parsed entity must not contain a recursive reference to itself, +either directly or indirectly. +

+ + +In DTD +

+Parameter-entity references may only appear in the +DTD. +

+ +

Examples of character and entity references: +Type <key>less-than</key> (&hcro;3C;) to save options. +This document was prepared on &docdate; and +is classified &security-level;.

Example of a parameter-entity reference: + + + +%ISOLat2;]]>

+ + + +Entity Declarations + +

+Entities are declared thus: + +Entity Declaration + +EntityDecl +GEDecl | PEDecl + + +GEDecl +'<!ENTITY' S Name +S EntityDef +S? '>' + +PEDecl +'<!ENTITY' S '%' S +Name S +PEDef S? '>' + + +EntityDef +EntityValue +| (ExternalID +NDataDecl?) + + + +PEDef +EntityValue +| ExternalID + + +The Name identifies the entity in an +entity reference or, in the case of an +unparsed entity, in the value of an ENTITY or ENTITIES +attribute. +If the same entity is declared more than once, the first declaration +encountered is binding; at user option, an XML processor may issue a +warning if entities are declared multiple times. +

+ + +Internal Entities + +

If +the entity definition is an +EntityValue, +the defined entity is called an internal entity. +There is no separate physical +storage object, and the content of the entity is given in the +declaration. +Note that some processing of entity and character references in the +literal entity value may be required to +produce the correct replacement +text: see . +

An internal entity is a parsed +entity.

Example of an internal entity declaration: +<!ENTITY Pub-Status "This is a pre-release of the + specification.">

+ + + +External Entities + +

If the entity is not +internal, it is an external +entity, declared as follows: + +External Entity Declaration + +ExternalID +'SYSTEM' S +SystemLiteral +| 'PUBLIC' S +PubidLiteral +S +SystemLiteral + + +NDataDecl +S 'NDATA' S +Name + + +If the NDataDecl is present, this is a +general unparsed +entity; otherwise it is a parsed entity.

+ +Notation Declared +

+The Name must match the declared name of a +notation. +

+ +

The +SystemLiteral +is called the entity's system identifier. It is a URI, +which may be used to retrieve the entity. +Note that the hash mark (#) and fragment identifier +frequently used with URIs are not, formally, part of the URI itself; +an XML processor may signal an error if a fragment identifier is +given as part of a system identifier. +Unless otherwise provided by information outside the scope of this +specification (e.g. a special XML element type defined by a particular +DTD, or a processing instruction defined by a particular application +specification), relative URIs are relative to the location of the +resource within which the entity declaration occurs. +A URI might thus be relative to the +document entity, to the entity +containing the external DTD subset, +or to some other external parameter entity. +

An XML processor should handle a non-ASCII character in a URI by +representing the character in UTF-8 as one or more bytes, and then +escaping these bytes with the URI escaping mechanism (i.e., by +converting each byte to %HH, where HH is the hexadecimal notation of the +byte value).

+In addition to a system identifier, an external identifier may +include a public identifier. +An XML processor attempting to retrieve the entity's content may use the public +identifier to try to generate an alternative URI. If the processor +is unable to do so, it must use the URI specified in the system +literal. Before a match is attempted, all strings +of white space in the public identifier must be normalized to single space characters (#x20), +and leading and trailing white space must be removed.

Examples of external entity declarations: +<!ENTITY open-hatch + SYSTEM "http://www.textuality.com/boilerplate/OpenHatch.xml"> +<!ENTITY open-hatch + PUBLIC "-//Textuality//TEXT Standard open-hatch boilerplate//EN" + "http://www.textuality.com/boilerplate/OpenHatch.xml"> +<!ENTITY hatch-pic + SYSTEM "../grafix/OpenHatch.gif" + NDATA gif >

+ + + + + +Parsed Entities + +The Text Declaration +

External parsed entities may each begin with a text +declaration. + +Text Declaration + +TextDecl +&xmlpio; +VersionInfo? +EncodingDecl +S? &pic; + + + +

The text declaration must be provided literally, not +by reference to a parsed entity. +No text declaration may appear at any position other than the beginning of +an external parsed entity.

+ + +Well-Formed Parsed Entities +

The document entity is well-formed if it matches the production labeled +document. +An external general +parsed entity is well-formed if it matches the production labeled +extParsedEnt. +An external parameter +entity is well-formed if it matches the production labeled +extPE. + +Well-Formed External Parsed Entity +extParsedEnt +TextDecl? +content + +extPE +TextDecl? +extSubsetDecl + + +An internal general parsed entity is well-formed if its replacement text +matches the production labeled +content. +All internal parameter entities are well-formed by definition. +

A consequence of well-formedness in entities is that the logical +and physical structures in an XML document are properly nested; no +start-tag, +end-tag, +empty-element tag, +element, +comment, +processing instruction, +character +reference, or +entity reference +can begin in one entity and end in another.

+ + +Character Encoding in Entities + +

Each external parsed entity in an XML document may use a different +encoding for its characters. All XML processors must be able to read +entities in either UTF-8 or UTF-16. + +

Entities encoded in UTF-16 must +begin with the Byte Order Mark described by ISO/IEC 10646 Annex E and +Unicode Appendix B (the ZERO WIDTH NO-BREAK SPACE character, #xFEFF). +This is an encoding signature, not part of either the markup or the +character data of the XML document. +XML processors must be able to use this character to +differentiate between UTF-8 and UTF-16 encoded documents.

Although an XML processor is required to read only entities in +the UTF-8 and UTF-16 encodings, it is recognized that other encodings are +used around the world, and it may be desired for XML processors +to read entities that use them. +Parsed entities which are stored in an encoding other than +UTF-8 or UTF-16 must begin with a text +declaration containing an encoding declaration: + +Encoding Declaration +EncodingDecl +S +'encoding' Eq +('"' EncName '"' | +"'" EncName "'" ) + + +EncName +[A-Za-z] ([A-Za-z0-9._] | '-')* +Encoding name contains only Latin characters + + +In the document entity, the encoding +declaration is part of the XML declaration. +The EncName is the name of the encoding used. +

+ +

In an encoding declaration, the values +"UTF-8", +"UTF-16", +"ISO-10646-UCS-2", and +"ISO-10646-UCS-4" should be +used for the various encodings and transformations of Unicode / +ISO/IEC 10646, the values +"ISO-8859-1", +"ISO-8859-2", ... +"ISO-8859-9" should be used for the parts of ISO 8859, and +the values +"ISO-2022-JP", +"Shift_JIS", and +"EUC-JP" +should be used for the various encoded forms of JIS X-0208-1997. XML +processors may recognize other encodings; it is recommended that +character encodings registered (as charsets) +with the Internet Assigned Numbers +Authority , other than those just listed, should be +referred to +using their registered names. +Note that these registered names are defined to be +case-insensitive, so processors wishing to match against them +should do so in a case-insensitive +way.

In the absence of information provided by an external +transport protocol (e.g. HTTP or MIME), +it is an error for an entity including +an encoding declaration to be presented to the XML processor +in an encoding other than that named in the declaration, +for an encoding declaration to occur other than at the beginning +of an external entity, or for +an entity which begins with neither a Byte Order Mark nor an encoding +declaration to use an encoding other than UTF-8. +Note that since ASCII +is a subset of UTF-8, ordinary ASCII entities do not strictly need +an encoding declaration.

+ +

It is a fatal error when an XML processor +encounters an entity with an encoding that it is unable to process.

Examples of encoding declarations: +<?xml encoding='UTF-8'?> +<?xml encoding='EUC-JP'?>

+ + + +XML Processor Treatment of Entities and References +

The table below summarizes the contexts in which character references, +entity references, and invocations of unparsed entities might appear and the +required behavior of an XML processor in +each case. +The labels in the leftmost column describe the recognition context: + +Reference in Content +

as a reference +anywhere after the start-tag and +before the end-tag of an element; corresponds +to the nonterminal content.

+ + +Reference in Attribute Value +

as a reference within either the value of an attribute in a +start-tag, or a default +value in an attribute declaration; +corresponds to the nonterminal +AttValue.

+ +Occurs as Attribute Value +

as a Name, not a reference, appearing either as +the value of an +attribute which has been declared as type ENTITY, or as one of +the space-separated tokens in the value of an attribute which has been +declared as type ENTITIES.

+ +Reference in Entity Value +

as a reference +within a parameter or internal entity's +literal entity value in +the entity's declaration; corresponds to the nonterminal +EntityValue.

+Reference in DTD +

as a reference within either the internal or external subsets of the +DTD, but outside +of an EntityValue or +AttValue.

+ +

+ + + +Entity Type +Character + + +Parameter +Internal +General +External Parsed +General +Unparsed + + + +Reference +in Content +Not recognized +Included +Included if validating +Forbidden +Included + + +Reference +in Attribute Value +Not recognized +Included in literal +Forbidden +Forbidden +Included + + +Occurs as +Attribute Value +Not recognized +Forbidden +Forbidden +Notify +Not recognized + + +Reference +in EntityValue +Included in literal +Bypassed +Bypassed +Forbidden +Included + + +Reference +in DTD +Included as PE +Forbidden +Forbidden +Forbidden +Forbidden + + + + +Not Recognized +

Outside the DTD, the % character has no +special significance; thus, what would be parameter entity references in the +DTD are not recognized as markup in content. +Similarly, the names of unparsed entities are not recognized except +when they appear in the value of an appropriately declared attribute. +

+ + +Included +

An entity is +included when its +replacement text is retrieved +and processed, in place of the reference itself, +as though it were part of the document at the location the +reference was recognized. +The replacement text may contain both +character data +and (except for parameter entities) markup, +which must be recognized in +the usual way, except that the replacement text of entities used to escape +markup delimiters (the entities &magicents;) is always treated as +data. (The string "AT&T;" expands to +"AT&T;" and the remaining ampersand is not recognized +as an entity-reference delimiter.) +A character reference is included when the indicated +character is processed in place of the reference itself. +

+ + +Included If Validating +

When an XML processor recognizes a reference to a parsed entity, in order +to validate +the document, the processor must +include its +replacement text. +If the entity is external, and the processor is not +attempting to validate the XML document, the +processor may, but need not, +include the entity's replacement text. +If a non-validating parser does not include the replacement text, +it must inform the application that it recognized, but did not +read, the entity.

This rule is based on the recognition that the automatic inclusion +provided by the SGML and XML entity mechanism, primarily designed +to support modularity in authoring, is not necessarily +appropriate for other applications, in particular document browsing. +Browsers, for example, when encountering an external parsed entity reference, +might choose to provide a visual indication of the entity's +presence and retrieve it for display only on demand. +

+ + +Forbidden +

The following are forbidden, and constitute +fatal errors: + +

the appearance of a reference to an +unparsed entity. +

the appearance of any character or general-entity reference in the +DTD except within an EntityValue or +AttValue.

a reference to an external entity in an attribute value.

+ + +

+ + +Included in Literal +

When an entity reference appears in an +attribute value, or a parameter entity reference appears in a literal entity +value, its replacement text is +processed in place of the reference itself as though it +were part of the document at the location the reference was recognized, +except that a single or double quote character in the replacement text +is always treated as a normal data character and will not terminate the +literal. +For example, this is well-formed: + +]]> +while this is not: +<!ENTITY EndAttr "27'" > +<element attribute='a-&EndAttr;> +

+ +Notify +

When the name of an unparsed +entity appears as a token in the +value of an attribute of declared type ENTITY or ENTITIES, +a validating processor must inform the +application of the system +and public (if any) +identifiers for both the entity and its associated +notation.

+ + +Bypassed +

When a general entity reference appears in the +EntityValue in an entity declaration, +it is bypassed and left as is.

+ + +Included as PE +

Just as with external parsed entities, parameter entities +need only be included if +validating. +When a parameter-entity reference is recognized in the DTD +and included, its +replacement +text is enlarged by the attachment of one leading and one following +space (#x20) character; the intent is to constrain the replacement +text of parameter +entities to contain an integral number of grammatical tokens in the DTD. +

+ + + + +Construction of Internal Entity Replacement Text +

In discussing the treatment +of internal entities, it is +useful to distinguish two forms of the entity's value. +The literal +entity value is the quoted string actually +present in the entity declaration, corresponding to the +non-terminal EntityValue. +The replacement +text is the content of the entity, after +replacement of character references and parameter-entity +references. +

+ +

The literal entity value +as given in an internal entity declaration +(EntityValue) may contain character, +parameter-entity, and general-entity references. +Such references must be contained entirely within the +literal entity value. +The actual replacement text that is +included as described above +must contain the replacement text of any +parameter entities referred to, and must contain the character +referred to, in place of any character references in the +literal entity value; however, +general-entity references must be left as-is, unexpanded. +For example, given the following declarations: + + + +]]> +then the replacement text for the entity "book" is: +La Peste: Albert Camus, +© 1947 Éditions Gallimard. &rights; +The general-entity reference "&rights;" would be expanded +should the reference "&book;" appear in the document's +content or an attribute value.

These simple rules may have complex interactions; for a detailed +discussion of a difficult example, see +. +

+ + + +Predefined Entities +

Entity and character +references can both be used to escape the left angle bracket, +ampersand, and other delimiters. A set of general entities +(&magicents;) is specified for this purpose. +Numeric character references may also be used; they are +expanded immediately when recognized and must be treated as +character data, so the numeric character references +"<" and "&" may be used to +escape < and & when they occur +in character data.

All XML processors must recognize these entities whether they +are declared or not. +For interoperability, +valid XML documents should declare these +entities, like any others, before using them. +If the entities in question are declared, they must be declared +as internal entities whose replacement text is the single +character being escaped or a character reference to +that character, as shown below. + + + + + +]]> +Note that the < and & characters +in the declarations of "lt" and "amp" +are doubly escaped to meet the requirement that entity replacement +be well-formed. +

+ + + +Notation Declarations + +

Notations identify by +name the format of unparsed +entities, the +format of elements which bear a notation attribute, +or the application to which +a processing instruction is +addressed.

+Notation declarations +provide a name for the notation, for use in +entity and attribute-list declarations and in attribute specifications, +and an external identifier for the notation which may allow an XML +processor or its client application to locate a helper application +capable of processing data in the given notation. + +Notation Declarations +NotationDecl +'<!NOTATION' S Name +S +(ExternalID | +PublicID) +S? '>' +PublicID +'PUBLIC' S +PubidLiteral + + +

XML processors must provide applications with the name and external +identifier(s) of any notation declared and referred to in an attribute +value, attribute definition, or entity declaration. They may +additionally resolve the external identifier into the +system identifier, +file name, or other information needed to allow the +application to call a processor for data in the notation described. (It +is not an error, however, for XML documents to declare and refer to +notations for which notation-specific applications are not available on +the system where the XML processor or application is running.)

+ + + + +Document Entity + +

The document +entity serves as the root of the entity +tree and a starting-point for an XML +processor. +This specification does +not specify how the document entity is to be located by an XML +processor; unlike other entities, the document entity has no name and might +well appear on a processor input stream +without any identification at all.

+ + + + + + + +Conformance + + +Validating and Non-Validating Processors +

Conforming XML processors fall into two +classes: validating and non-validating.

Validating and non-validating processors alike must report +violations of this specification's well-formedness constraints +in the content of the +document entity and any +other parsed entities that +they read.

+Validating processors must report +violations of the constraints expressed by the declarations in the +DTD, and +failures to fulfill the validity constraints given +in this specification. + +To accomplish this, validating XML processors must read and process the entire +DTD and all external parsed entities referenced in the document. +

Non-validating processors are required to check only the +document entity, including +the entire internal DTD subset, for well-formedness. + +While they are not required to check the document for validity, +they are required to +process all the declarations they read in the +internal DTD subset and in any parameter entity that they +read, up to the first reference +to a parameter entity that they do not read; that is to +say, they must +use the information in those declarations to +normalize attribute values, +include the replacement text of +internal entities, and supply +default attribute values. + +They must not process +entity declarations or +attribute-list declarations +encountered after a reference to a parameter entity that is not +read, since the entity may have contained overriding declarations. +

+ + +Using XML Processors +

The behavior of a validating XML processor is highly predictable; it +must read every piece of a document and report all well-formedness and +validity violations. +Less is required of a non-validating processor; it need not read any +part of the document other than the document entity. +This has two effects that may be important to users of XML processors: + +

Certain well-formedness errors, specifically those that require +reading external entities, may not be detected by a non-validating processor. +Examples include the constraints entitled +Entity Declared, +Parsed Entity, and +No Recursion, as well +as some of the cases described as +forbidden in +.

The information passed from the processor to the application may +vary, depending on whether the processor reads +parameter and external entities. +For example, a non-validating processor may not +normalize attribute values, +include the replacement text of +internal entities, or supply +default attribute values, +where doing so depends on having read declarations in +external or parameter entities.

+ +

For maximum reliability in interoperating between different XML +processors, applications which use non-validating processors should not +rely on any behaviors not required of such processors. +Applications which require facilities such as the use of default +attributes or internal entities which are declared in external +entities should use validating XML processors.

+ + + + +Notation + +

The formal grammar of XML is given in this specification using a simple +Extended Backus-Naur Form (EBNF) notation. Each rule in the grammar defines +one symbol, in the form +symbol ::= expression

Symbols are written with an initial capital letter if they are +defined by a regular expression, or with an initial lower case letter +otherwise. +Literal strings are quoted. + +

+ +

Within the expression on the right-hand side of a rule, the following +expressions are used to match strings of one or more characters: + + +#xN +

where N is a hexadecimal integer, the +expression matches the character in ISO/IEC 10646 whose canonical +(UCS-4) +code value, when interpreted as an unsigned binary number, has +the value indicated. The number of leading zeros in the +#xN form is insignificant; the number of leading +zeros in the corresponding code value +is governed by the character +encoding in use and is not significant for XML.

+ + +[a-zA-Z], [#xN-#xN] +

matches any character +with a value in the range(s) indicated (inclusive).

+ + +[^a-z], [^#xN-#xN] +

matches any character +with a value outside the +range indicated.

+ + +[^abc], [^#xN#xN#xN] +

matches any character +with a value not among the characters given.

+ + +"string" +

matches a literal string matching +that given inside the double quotes.

+ + +'string' +

matches a literal string matching +that given inside the single quotes.

+ + +These symbols may be combined to match more complex patterns as follows, +where A and B represent simple expressions: + + +(expression) +

expression is treated as a unit +and may be combined as described in this list.

+ + +A? +

matches A or nothing; optional A.

+ + +A B +

matches A followed by B.

+ + +A | B +

matches A or B but not both.

+ + +A - B +

matches any string that matches A but does not match +B. +

+ + +A+ +

matches one or more occurrences of A.

+ + +A* +

matches zero or more occurrences of A.

+ + + +Other notations used in the productions are: + + +/* ... */ +

comment.

+ + +[ wfc: ... ] +

well-formedness constraint; this identifies by name a +constraint on +well-formed documents +associated with a production.

+ + +[ vc: ... ] +

validity constraint; this identifies by name a constraint on +valid documents associated with +a production.

+ + +

+ + + + + + + + + +References + +Normative References + + + +(Internet Assigned Numbers Authority) Official Names for +Character Sets, +ed. Keld Simonsen et al. +See ftp://ftp.isi.edu/in-notes/iana/assignments/character-sets. + + + +IETF (Internet Engineering Task Force). +RFC 1766: Tags for the Identification of Languages, +ed. H. Alvestrand. +1995. + + + +(International Organization for Standardization). +ISO 639:1988 (E). +Code for the representation of names of languages. +[Geneva]: International Organization for +Standardization, 1988. + + +(International Organization for Standardization). +ISO 3166-1:1997 (E). +Codes for the representation of names of countries and their subdivisions +— Part 1: Country codes +[Geneva]: International Organization for +Standardization, 1997. + +ISO +(International Organization for Standardization). +ISO/IEC 10646-1993 (E). Information technology — Universal +Multiple-Octet Coded Character Set (UCS) — Part 1: +Architecture and Basic Multilingual Plane. +[Geneva]: International Organization for +Standardization, 1993 (plus amendments AM 1 through AM 7). + + +The Unicode Consortium. +The Unicode Standard, Version 2.0. +Reading, Mass.: Addison-Wesley Developers Press, 1996. + + + + + +Other References + + + +Aho, Alfred V., +Ravi Sethi, and Jeffrey D. Ullman. +Compilers: Principles, Techniques, and Tools. +Reading: Addison-Wesley, 1986, rpt. corr. 1988. + + +Berners-Lee, T., R. Fielding, and L. Masinter. +Uniform Resource Identifiers (URI): Generic Syntax and +Semantics. +1997. +(Work in progress; see updates to RFC1738.) + +Brüggemann-Klein, Anne. +Regular Expressions into Finite Automata. +Extended abstract in I. Simon, Hrsg., LATIN 1992, +S. 97-98. Springer-Verlag, Berlin 1992. +Full Version in Theoretical Computer Science 120: 197-213, 1993. + + + +Brüggemann-Klein, Anne, +and Derick Wood. +Deterministic Regular Languages. +Universität Freiburg, Institut für Informatik, +Bericht 38, Oktober 1991. + + +James Clark. +Comparison of SGML and XML. See +http://www.w3.org/TR/NOTE-sgml-xml-971215. + + +IETF (Internet Engineering Task Force). +RFC 1738: Uniform Resource Locators (URL), +ed. T. Berners-Lee, L. Masinter, M. McCahill. +1994. + + + +IETF (Internet Engineering Task Force). +RFC 1808: Relative Uniform Resource Locators, +ed. R. Fielding. +1995. + + + +IETF (Internet Engineering Task Force). +RFC 2141: URN Syntax, +ed. R. Moats. +1997. + + +ISO +(International Organization for Standardization). +ISO 8879:1986(E). Information processing — Text and Office +Systems — Standard Generalized Markup Language (SGML). First +edition — 1986-10-15. [Geneva]: International Organization for +Standardization, 1986. + + + +ISO +(International Organization for Standardization). +ISO/IEC 10744-1992 (E). Information technology — +Hypermedia/Time-based Structuring Language (HyTime). + +[Geneva]: International Organization for +Standardization, 1992. +Extended Facilities Annexe. +[Geneva]: International Organization for +Standardization, 1996. + + + + + + + + +Character Classes +

The character classes defined here can be derived from the +Unicode character database as follows: + + +

Name start characters must have one of the categories Ll, Lu, +Lo, Lt, Nl.

+ + +

Name characters other than Name-start characters +must have one of the categories Mc, Me, Mn, Lm, or Nd.

+ + +

Characters in the compatibility area (i.e. with character code +greater than #xF900 and less than #xFFFE) are not allowed in XML +names.

+ + +

Characters which have a font or compatibility decomposition (i.e. those +with a "compatibility formatting tag" in field 5 of the database -- +marked by field 5 beginning with a "<") are not allowed.

+ + +

The following characters are treated as name-start characters +rather than name characters, because the property file classifies +them as Alphabetic: [#x02BB-#x02C1], #x0559, #x06E5, #x06E6.

+ + +

Characters #x20DD-#x20E0 are excluded (in accordance with +Unicode, section 5.14).

+ + +

Character #x00B7 is classified as an extender, because the +property list so identifies it.

+ + +

Character #x0387 is added as a name character, because #x00B7 +is its canonical equivalent.

+ + +

Characters ':' and '_' are allowed as name-start characters.

+ + +

Characters '-' and '.' are allowed as name characters.

+ + +

+ + +XML and SGML + +

XML is designed to be a subset of SGML, in that every +valid XML document should also be a +conformant SGML document. +For a detailed comparison of the additional restrictions that XML places on +documents beyond those of SGML, see . +

+ + +Expansion of Entity and Character References +

This appendix contains some examples illustrating the +sequence of entity- and character-reference recognition and +expansion, as specified in .

+If the DTD contains the declaration +An ampersand (&) may be escaped +numerically (&#38;) or with a general entity +(&).

" > +]]> +then the XML processor will recognize the character references +when it parses the entity declaration, and resolve them before +storing the following string as the +value of the entity "example": +An ampersand (&) may be escaped +numerically (&) or with a general entity +(&).

+]]> +A reference in the document to "&example;" +will cause the text to be reparsed, at which time the +start- and end-tags of the "p" element will be recognized +and the three references will be recognized and expanded, +resulting in a "p" element with the following content +(all data, no delimiters or markup): + +

A more complex example will illustrate the rules and their +effects fully. In the following example, the line numbers are +solely for reference. + +2 +4 +5 ' > +6 %xx; +7 ]> +8 This sample shows a &tricky; method. +]]> +This produces the following: + +

in line 4, the reference to character 37 is expanded immediately, +and the parameter entity "xx" is stored in the symbol +table with the value "%zz;". Since the replacement text +is not rescanned, the reference to parameter entity "zz" +is not recognized. (And it would be an error if it were, since +"zz" is not yet declared.)

in line 5, the character reference "<" is +expanded immediately and the parameter entity "zz" is +stored with the replacement text +"<!ENTITY tricky "error-prone" >", +which is a well-formed entity declaration.

in line 6, the reference to "xx" is recognized, +and the replacement text of "xx" (namely +"%zz;") is parsed. The reference to "zz" +is recognized in its turn, and its replacement text +("<!ENTITY tricky "error-prone" >") is parsed. +The general entity "tricky" has now been +declared, with the replacement text "error-prone".

+in line 8, the reference to the general entity "tricky" is +recognized, and it is expanded, so the full content of the +"test" element is the self-describing (and ungrammatical) string +This sample shows a error-prone method. +

+ +

+ + +Deterministic Content Models +

For compatibility, it is +required +that content models in element type declarations be deterministic. +

+ +

SGML +requires deterministic content models (it calls them +"unambiguous"); XML processors built using SGML systems may +flag non-deterministic content models as errors.

For example, the content model ((b, c) | (b, d)) is +non-deterministic, because given an initial b the parser +cannot know which b in the model is being matched without +looking ahead to see which element follows the b. +In this case, the two references to +b can be collapsed +into a single reference, making the model read +(b, (c | d)). An initial b now clearly +matches only a single name in the content model. The parser doesn't +need to look ahead to see what follows; either c or +d would be accepted.

More formally: a finite state automaton may be constructed from the +content model using the standard algorithms, e.g. algorithm 3.5 +in section 3.9 +of Aho, Sethi, and Ullman . +In many such algorithms, a follow set is constructed for each +position in the regular expression (i.e., each leaf +node in the +syntax tree for the regular expression); +if any position has a follow set in which +more than one following position is +labeled with the same element type name, +then the content model is in error +and may be reported as an error. +

Algorithms exist which allow many but not all non-deterministic +content models to be reduced automatically to equivalent deterministic +models; see Brüggemann-Klein 1991 .

+ + +Autodetection of Character Encodings +

The XML encoding declaration functions as an internal label on each +entity, indicating which character encoding is in use. Before an XML +processor can read the internal label, however, it apparently has to +know what character encoding is in use—which is what the internal label +is trying to indicate. In the general case, this is a hopeless +situation. It is not entirely hopeless in XML, however, because XML +limits the general case in two ways: each implementation is assumed +to support only a finite set of character encodings, and the XML +encoding declaration is restricted in position and content in order to +make it feasible to autodetect the character encoding in use in each +entity in normal cases. Also, in many cases other sources of information +are available in addition to the XML data stream itself. +Two cases may be distinguished, +depending on whether the XML entity is presented to the +processor without, or with, any accompanying +(external) information. We consider the first case first. +

+Because each XML entity not in UTF-8 or UTF-16 format must +begin with an XML encoding declaration, in which the first characters +must be '<?xml', any conforming processor can detect, +after two to four octets of input, which of the following cases apply. +In reading this list, it may help to know that in UCS-4, '<' is +"#x0000003C" and '?' is "#x0000003F", and the Byte +Order Mark required of UTF-16 data streams is "#xFEFF".

+ + +

00 00 00 3C: UCS-4, big-endian machine (1234 order)

+ + +

3C 00 00 00: UCS-4, little-endian machine (4321 order)

+ + +

00 00 3C 00: UCS-4, unusual octet order (2143)

+ + +

00 3C 00 00: UCS-4, unusual octet order (3412)

+ + +

FE FF: UTF-16, big-endian

+ + +

FF FE: UTF-16, little-endian

+ + +

00 3C 00 3F: UTF-16, big-endian, no Byte Order Mark +(and thus, strictly speaking, in error)

+ + +

3C 00 3F 00: UTF-16, little-endian, no Byte Order Mark +(and thus, strictly speaking, in error)

+ + +

3C 3F 78 6D: UTF-8, ISO 646, ASCII, some part of ISO 8859, +Shift-JIS, EUC, or any other 7-bit, 8-bit, or mixed-width encoding +which ensures that the characters of ASCII have their normal positions, +width, +and values; the actual encoding declaration must be read to +detect which of these applies, but since all of these encodings +use the same bit patterns for the ASCII characters, the encoding +declaration itself may be read reliably +

+ + +

4C 6F A7 94: EBCDIC (in some flavor; the full +encoding declaration must be read to tell which code page is in +use)

+ + +

other: UTF-8 without an encoding declaration, or else +the data stream is corrupt, fragmentary, or enclosed in +a wrapper of some kind

+ + +

+This level of autodetection is enough to read the XML encoding +declaration and parse the character-encoding identifier, which is +still necessary to distinguish the individual members of each family +of encodings (e.g. to tell UTF-8 from 8859, and the parts of 8859 +from each other, or to distinguish the specific EBCDIC code page in +use, and so on). +

+Because the contents of the encoding declaration are restricted to +ASCII characters, a processor can reliably read the entire encoding +declaration as soon as it has detected which family of encodings is in +use. Since in practice, all widely used character encodings fall into +one of the categories above, the XML encoding declaration allows +reasonably reliable in-band labeling of character encodings, even when +external sources of information at the operating-system or +transport-protocol level are unreliable. +

+Once the processor has detected the character encoding in use, it can +act appropriately, whether by invoking a separate input routine for +each case, or by calling the proper conversion function on each +character of input. +

+Like any self-labeling system, the XML encoding declaration will not +work if any software changes the entity's character set or encoding +without updating the encoding declaration. Implementors of +character-encoding routines should be careful to ensure the accuracy +of the internal and external information used to label the entity. +

The second possible case occurs when the XML entity is accompanied +by encoding information, as in some file systems and some network +protocols. +When multiple sources of information are available, + +their relative +priority and the preferred method of handling conflict should be +specified as part of the higher-level protocol used to deliver XML. +Rules for the relative priority of the internal label and the +MIME-type label in an external header, for example, should be part of the +RFC document defining the text/xml and application/xml MIME types. In +the interests of interoperability, however, the following rules +are recommended. + +

If an XML entity is in a file, the Byte-Order Mark +and encoding-declaration PI are used (if present) to determine the +character encoding. All other heuristics and sources of information +are solely for error recovery. +

If an XML entity is delivered with a +MIME type of text/xml, then the charset parameter +on the MIME type determines the +character encoding method; all other heuristics and sources of +information are solely for error recovery. +

If an XML entity is delivered +with a +MIME type of application/xml, then the Byte-Order Mark and +encoding-declaration PI are used (if present) to determine the +character encoding. All other heuristics and sources of +information are solely for error recovery. +

+ +These rules apply only in the absence of protocol-level documentation; +in particular, when the MIME types text/xml and application/xml are +defined, the recommendations of the relevant RFC will supersede +these rules. +

+ + + + +W3C XML Working Group + +

This specification was prepared and approved for publication by the +W3C XML Working Group (WG). WG approval of this specification does +not necessarily imply that all WG members voted for its approval. +The current and former members of the XML WG are:

+ + +Jon Bosak, SunChair +James ClarkTechnical Lead +Tim Bray, Textuality and NetscapeXML Co-editor +Jean Paoli, MicrosoftXML Co-editor +C. M. Sperberg-McQueen, U. of Ill.XML +Co-editor +Dan Connolly, W3CW3C Liaison +Paula Angerstein, Texcel +Steve DeRose, INSO +Dave Hollander, HP +Eliot Kimber, ISOGEN +Eve Maler, ArborText +Tom Magliery, NCSA +Murray Maloney, Muzmo and Grif +Makoto Murata, Fuji Xerox Information Systems +Joel Nava, Adobe +Conleth O'Connell, Vignette +Peter Sharpe, SoftQuad +John Tigue, DataChannel + + + + + + diff --git a/samples/canonical b/samples/canonical new file mode 100755 index 0000000..e7c5455 --- /dev/null +++ b/samples/canonical @@ -0,0 +1,124 @@ +#!/usr/local/bin/perl -w +# +# Copyright 1999 Clark Cooper +# All rights reserved. +# +# This program is free software; you can redistribute it and/or +# modify it under the same terms as Perl itself. +# +# $Revision: 1.1.1.1 $ +# +# $Date: 2003-07-27 11:07:11 $ +# +# This program take an XML document (either on standard input or +# from a filename supplied as an argument) and generates corresponding +# canonical XML document on the standard output. The definition of +# "Canonical XML" that I'm using is taken from the working draft +# published by W3C on 19-Jan-2000: +# +# http://www.w3.org/TR/2000/WD-xml-c14n-20000119.html +# +# The latest version of this document is at: +# +# http://www.w3.org/TR/xml-c14n +# + +use XML::Parser; + +my $indoctype = 0; +my $inroot = 0; +my $p = new XML::Parser(ErrorContext => 2, + Namespaces => 1, + ParseParamEnt => 1, + Handlers => {Start => \&sthndl, + End => \&endhndl, + Char => \&chrhndl, + Proc => \&proc, + Doctype => sub {$indoctype = 1}, + DoctypeFin => sub {$indoctype = 0} + } + ); + +my $file = shift; +if (defined $file) { + $p->parsefile($file); +} +else { + $p->parse(*STDIN); +} + +################ +## End main +################ + +sub sthndl { + my $xp = shift; + my $el = shift; + + $inroot = 1 unless $inroot; + my $ns_index = 1; + + my $elns = $xp->namespace($el); + if (defined $elns) { + my $pfx = 'n' . $ns_index++; + print "<$pfx:$el xmlns:$pfx=\"$elns\""; + } + else { + print "<$el"; + } + + if (@_) { + for (my $i = 0; $i < @_; $i += 2) { + my $nm = $_[$i]; + my $ns = $xp->namespace($nm); + $_[$i] = defined($ns) ? "$ns\01$nm" : "\01$nm"; + } + + my %atts = @_; + my @ids = sort keys %atts; + foreach my $id (@ids) { + my ($ns, $nm) = split(/\01/, $id); + my $val = $xp->xml_escape($atts{$id}, '"', "\x9", "\xA", "\xD"); + if (length($ns)) { + my $pfx = 'n' . $ns_index++; + print " $pfx:$nm=\"$val\" xmlns:$pfx=\"$ns\""; + } + else { + print " $nm=\"$val\""; + } + } + } + + print '>'; +} # End sthndl + +sub endhndl { + my ($xp, $el) = @_; + + my $nm = $xp->namespace($el) ? "n1:$el" : $el; + print ""; + if ($xp->depth == 0) { + $inroot = 0; + print "\n"; + } +} # End endhndl + +sub chrhndl { + my ($xp, $data) = @_; + + print $xp->xml_escape($data, '>', "\xD"); +} # End chrhndl + +sub proc { + my ($xp, $target, $data) = @_; + + unless ($indoctype) { + print ""; + print "\n" unless $inroot; + } +} + +# Tell emacs that this is really a perl script +#Local Variables: +#mode: perl +#End: diff --git a/samples/canontst.xml b/samples/canontst.xml new file mode 100644 index 0000000..e01ef77 --- /dev/null +++ b/samples/canontst.xml @@ -0,0 +1,20 @@ + + + + ] +> + + + + + + Here is a PI: . Like it? + + + + \ No newline at end of file diff --git a/samples/ctest.dtd b/samples/ctest.dtd new file mode 100644 index 0000000..4882cf2 --- /dev/null +++ b/samples/ctest.dtd @@ -0,0 +1,2 @@ + + diff --git a/samples/xmlcomments b/samples/xmlcomments new file mode 100755 index 0000000..3b066ae --- /dev/null +++ b/samples/xmlcomments @@ -0,0 +1,44 @@ +#!/usr/local/bin/perl -w +# +# $Revision: 1.1.1.1 $ +# +# $Date: 2003-07-27 11:07:11 $ + +use XML::Parser; + +my $file = shift; + +die "Can't find file \"$file\"" + unless -f $file; + +my $count = 0; + +my $parser = new XML::Parser(ErrorContext => 2, + ParseParamEnt => 0 + ); + +$parser->setHandlers(Comment => \&comments); + +$parser->parsefile($file); + +print "Found $count comments.\n"; + +################ +## End of main +################ + +sub comments +{ + my ($p, $data) = @_; + + my $line = $p->current_line; + $data =~ s/\n/\n\t/g; + print "$line:\t\n"; + $count++; + +} # End comments + +# Tell Emacs that this is really a perl script +# Local Variables: +# mode:perl +# End: diff --git a/samples/xmlfilter b/samples/xmlfilter new file mode 100755 index 0000000..ddbc5b5 --- /dev/null +++ b/samples/xmlfilter @@ -0,0 +1,329 @@ +#!/usr/local/bin/perl -w +# +# $Revision: 1.1.1.1 $ +# +# $Date: 2003-07-27 11:07:11 $ + +use XML::Parser; + +my $Usage =<<'End_of_Usage;'; +Usage is: + xmlfilter [-h] [-nl] [{-+}root] [{-+}el=elname] [{-+}el:elnamepat] + [{-+}att:attname] [{-+}att:attname:attvalpat] xmlfile + +Prints on standard output the result of filtering the given xmlfile +for elements according to the switches. A '-' option will drop the +element from the output; a '+' will keep it. The output should also +be a well-formed XML document. + + -h Print this message + + -nl Emit a newline prior to every start tag. + + [-+]root Drop (or keep) the root element. Defaults to keep. + If the root element were named "foo", then -root + would be equivalent to -el=foo. Note that even if + you're dropping the root element, it's start and + end tag are kept in order that the output remains + a well-formed XML document. + + [-+]el=elname + Drop (or keep) elements of type elname. + + [-+]el:elnamepat + Drop (or keep) element whose type name matches elnamepat. + + [-+]att:attname + Drop (or keep) elements which have an attribute = attname. + + [-+]att:attname:attvalpat + Drop (or keep) elements which have an attribute = attname + and for which the attribute value matches attvalpat. +End_of_Usage; + +my $pass = 1; +my $do_newline = 0; + +my $attcheck = 0; + +my %drop_el; +my @drop_elpat; + +my %keep_el; +my @keep_elpat; + +my %drop_att; +my %keep_att; + +my $always_true = sub {1;}; +my $root_element = ''; + +my $in_cdata = 0; + +# Process options + +while (defined($ARGV[0]) and $ARGV[0] =~ /^[-+]/) +{ + my $opt = shift; + + if ($opt eq '-root') + { + $pass = 0; + } + elsif ($opt eq '+root') + { + $pass = 1; + } + elsif ($opt eq '-h') + { + print $Usage; + exit; + } + elsif ($opt eq '-nl') + { + $do_newline = 1; + } + elsif ($opt =~ /^([-+])el([:=])(\S*)/) + { + my ($disp, $kind, $pattern) = ($1, $2, $3); + my ($hashref, $aref); + + if ($disp eq '-') + { + $hashref = \%drop_el; + $aref = \@drop_elpat; + } + else + { + $hashref = \%keep_el; + $aref = \@keep_elpat; + } + + if ($kind eq '=') + { + $hashref->{$pattern} = 1; + } + else + { + push(@$aref, $pattern); + } + } + elsif ($opt =~ /^([-+])att:(\w+)(?::(\S*))?/) + { + my ($disp, $id, $pattern) = ($1, $2, $3); + my $ref = ($disp eq '-') ? \%drop_att : \%keep_att; + + if (defined($pattern)) + { + $pattern =~ s!/!\\/!g; + my $sub; + eval "\$sub = sub {\$_[0] =~ /$pattern/;};"; + + $ref->{$id} = $sub; + } + else + { + $ref->{$id} = $always_true; + } + + $attcheck = 1; + } + else + { + die "Unknown option: $opt\n$Usage"; + } +} + +my $drop_el_pattern = join('|', @drop_elpat); +my $keep_el_pattern = join('|', @keep_elpat); + +my $drop_sub; +if ($drop_el_pattern) +{ + eval "\$drop_sub = sub {\$_[0] =~ /$drop_el_pattern/;}"; +} +else +{ + $drop_sub = sub {}; +} + +my $keep_sub; +if ($keep_el_pattern) +{ + eval "\$keep_sub = sub {\$_[0] =~ /$keep_el_pattern/;}"; +} +else +{ + $keep_sub = sub {}; +} + +my $doc = shift; + +die "No file specified\n$Usage" unless defined($doc); + +my @togglestack = (); + +my $p = new XML::Parser(ErrorContext => 2, + Handlers => {Start => \&start_handler, + End => \&end_handler + } + ); + +if ($pass) { + $p->setHandlers(Char => \&char_handler, + CdataStart => \&cdata_start, + CdataEnd => \&cdata_end); +} + +$p->parsefile($doc); + +print "\n" + unless $pass; + +################ +## End of main +################ + +sub start_handler +{ + my $xp = shift; + my $el = shift; + + unless ($root_element) + { + $root_element = $el; + print "<$el>\n" + unless $pass; + } + + my ($elref, $attref, $sub); + + if ($pass) + { + $elref = \%drop_el; + $attref = \%drop_att; + $sub = $drop_sub; + } + else + { + $elref = \%keep_el; + $attref = \%keep_att; + $sub = $keep_sub; + } + + if (defined($elref->{$el}) + or &$sub($el) + or check_atts($attref, @_)) + { + $pass = ! $pass; + if ($pass) { + $xp->setHandlers(Char => \&char_handler, + CdataStart => \&cdata_start, + CdataEnd => \&cdata_end); + } + else { + $xp->setHandlers(Char => 0, + CdataStart => 0, + CdataEnd => 0); + } + push(@togglestack, $xp->depth); + } + + if ($pass) + { + print "\n" if $do_newline; + print "<$el"; + while (@_) + { + my $id = shift; + my $val = shift; + + $val = $xp->xml_escape($val, "'"); + print " $id='$val'"; + } + print ">"; + } +} # End start_handler + +sub end_handler +{ + my $xp = shift; + my $el = shift; + + if ($pass) + { + print ""; + } + + if (@togglestack and $togglestack[-1] == $xp->depth) + { + $pass = ! $pass; + if ($pass) { + $xp->setHandlers(Char => \&char_handler, + CdataStart => \&cdata_start, + CdataEnd => \&cdata_end); + } + else { + $xp->setHandlers(Char => 0, + CdataStart => 0, + CdataEnd => 0); + } + + pop(@togglestack); + } + +} # End end_handler + + +sub char_handler +{ + my ($xp, $text) = @_; + + if (length($text)) { + + $text = $xp->xml_escape($text, '>') + unless $in_cdata; + + print $text; + } +} # End char_handler + +sub cdata_start { + my $xp = shift; + + print ''; + $in_cdata = 0; +} + +sub check_atts +{ + return $attcheck unless $attcheck; + + my $ref = shift; + + while (@_) + { + my $id = shift; + my $val = shift; + + if (defined($ref->{$id})) + { + my $ret = &{$ref->{$id}}($val); + return $ret if $ret; + } + } + + return 0; +} # End check_atts + +# Tell Emacs that this is really a perl script +# Local Variables: +# mode:perl +# End: diff --git a/samples/xmlstats b/samples/xmlstats new file mode 100755 index 0000000..07d98d0 --- /dev/null +++ b/samples/xmlstats @@ -0,0 +1,186 @@ +#!/usr/local/bin/perl -w +# +# $Revision: 1.1.1.1 $ +# +# $Date: 2003-07-27 11:07:11 $ + +package Elinfo; + +sub new { + bless { COUNT => 0, + MINLEV => undef, + SEEN => 0, + CHARS => 0, + EMPTY => 1, + PTAB => {}, + KTAB => {}, + ATAB => {} }, shift; +} + + +package main; + +use English; +use XML::Parser; + +my %elements; +my $seen = 0; +my $root; + +my $file = shift; + +my $subform = + ' @<<<<<<<<<<<<<<< @>>>>'; +die "Can't find file \"$file\"" + unless -f $file; + +my $parser = new XML::Parser(ErrorContext => 2); +$parser->setHandlers(Start => \&start_handler, + Char => \&char_handler); + +$parser->parsefile($file); + +set_minlev($root, 0); + +my $el; + +foreach $el (sort bystruct keys %elements) +{ + my $ref = $elements{$el}; + print "\n================\n$el: ", $ref->{COUNT}, "\n"; + print "Had ", $ref->{CHARS}, " bytes of character data\n" + if $ref->{CHARS}; + print "Always empty\n" + if $ref->{EMPTY}; + + showtab('Parents', $ref->{PTAB}, 0); + showtab('Children', $ref->{KTAB}, 1); + showtab('Attributes', $ref->{ATAB}, 0); +} + + +################ +## End of main +################ + +sub start_handler +{ + my $p = shift; + my $el = shift; + + my $elinf = $elements{$el}; + + if (not defined($elinf)) + { + $elements{$el} = $elinf = new Elinfo; + $elinf->{SEEN} = $seen++; + } + + $elinf->{COUNT}++; + + my $partab = $elinf->{PTAB}; + + my $parent = $p->current_element; + if (defined($parent)) + { + $partab->{$parent}++; + my $pinf = $elements{$parent}; + + # Increment our slot in parent's child table + $pinf->{KTAB}->{$el}++; + $pinf->{EMPTY} = 0; + } + else + { + $root = $el; + } + + # Deal with attributes + + my $atab = $elinf->{ATAB}; + + while (@_) + { + my $att = shift; + + $atab->{$att}++; + shift; # Throw away value + } + +} # End start_handler + +sub char_handler +{ + my ($p, $data) = @_; + my $inf = $elements{$p->current_element}; + + $inf->{EMPTY} = 0; + if ($data =~ /\S/) + { + $inf->{CHARS} += length($data); + } +} # End char_handler + +sub set_minlev +{ + my ($el, $lev) = @_; + + my $elinfo = $elements{$el}; + if (! defined($elinfo->{MINLEV}) or $elinfo->{MINLEV} > $lev) + { + my $newlev = $lev + 1; + + $elinfo->{MINLEV} = $lev; + foreach (keys %{$elinfo->{KTAB}}) + { + set_minlev($_, $newlev); + } + } +} # End set_minlev + +sub bystruct +{ + my $refa = $elements{$a}; + my $refb = $elements{$b}; + + $refa->{MINLEV} <=> $refb->{MINLEV} + or $refa->{SEEN} <=> $refb->{SEEN}; +} # End bystruct + + +sub showtab +{ + my ($title, $table, $dosum) = @_; + + my @list = sort keys %{$table}; + + if (@list) + { + print "\n $title:\n"; + + my $item; + my $sum = 0; + foreach $item (@list) + { + my $cnt = $table->{$item}; + $sum += $cnt; + formline($subform, $item, $cnt); + print $ACCUMULATOR, "\n"; + $ACCUMULATOR = ''; + } + + if ($dosum and @list > 1) + { + print " =====\n"; + formline($subform, '', $sum); + print $ACCUMULATOR, "\n"; + $ACCUMULATOR = ''; + } + } + +} # End showtab + +# Tell Emacs that this is really a perl script +# Local Variables: +# mode:perl +# End: -- cgit v1.2.1