A couple small corrections to the content negotiation docs:

- The "parent language" matchine is available always, not just
with ForceLanguagePriority

- ForceLanguagePriority defaults to Prefer, not None.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@95354 13f79535-47bb-0310-9956-ffa450edef68

4 files changed, 46 insertions, 34 deletions

diff --git a/docs/manual/content-negotiation.html b/docs/manual/content-negotiation.html
index 8403cb2733..6b4c6a6f1a 100644
--- a/docs/manual/content-negotiation.html
+++ b/docs/manual/content-negotiation.html
@@ -208,7 +208,7 @@
     depends on the setting of the <a
     href="mod/mod_mime.html#multiviewsmatch">MultiViewsMatch</a>
     directive.  This directive determines whether handlers, filters,
-    and other file types can participate in MultiViews
+    and other extension types can participate in MultiViews
     negotiation.</p>
 
     <h2>The Negotiation Methods</h2>
@@ -426,6 +426,10 @@
 
     <h3>Language Negotiation Exceptions</h3>
 
+    <p>New in Apache 2.0, some exceptions have been added to the
+    negotiation algorithm to allow graceful fallback when language
+    negotiation fails to find a match.</p>
+
     <p>When a client requests a page on your server, but the server
     cannot find a single page that matches the Accept-language sent by
     the browser, the server will return either a "No Acceptable
@@ -439,26 +443,28 @@
     href="mod_negotiation.html#languagepriority">LanguagePriority</a>
     directive.</p>
 
-    <p>The <code>ForceLanguagePriority</code> directive also causes
-    Apache to attempt to match language-subsets against their parent
-    language when no other match can be obtained.  For example, if a
-    client requests documents with the language <code>en-GB</code> for
-    British English, the server is not normally allowed by the
-    HTTP/1.1 standard to return a document that is marked as simply
+    <p>The server will also attempt to match language-subsets when no
+    other match can be found.  For example, if a client requests
+    documents with the language <code>en-GB</code> for British
+    English, the server is not normally allowed by the HTTP/1.1
+    standard to match that against a document that is marked as simply
     <code>en</code>.  (Note that it is almost surely a configuration
     error to include <code>en-GB</code> and not <code>en</code> in the
     Accept-Language header, since it is very unlikely that a reader
     understands British English, but doesn't understand English in
     general.  Unfortunately, many current clients have default
-    configurations that resemble this.)  With the
-    <code>ForceLanguagePriority</code> header, the server can be
-    configured to ignore the subset specification and match
-    <code>en-GB</code> against <code>en</code> documents.  But note
-    that if the client requests "en-GB; qs=0.9, fr; qs=0.8", and the
-    server has documents designated "en" and "fr", then the "fr"
-    document will be returned regardless of the
-    <code>ForceLanguagePriority</code> directive.  This is necessary
-    to maintain compliance with the HTTP/1.1 specification.</p>
+    configurations that resemble this.)  However, if no other language
+    match is possible and the server is about to return a "No
+    Acceptable Variants" error or fallback to the
+    <code>LanguagePriority</code>, the server will ignore the subset
+    specification and match <code>en-GB</code> against <code>en</code>
+    documents.  Implicitly, Apache will add the parent language to
+    the client's acceptable language list with a very low quality
+    value.  But note that if the client requests "en-GB; qs=0.9, fr;
+    qs=0.8", and the server has documents designated "en" and "fr",
+    then the "fr" document will be returned.  This is necessary to
+    maintain compliance with the HTTP/1.1 specification and to work
+    effectively with properly configured clients.</p>
 
 
     <h2>Extensions to Transparent Content Negotiation</h2>
diff --git a/docs/manual/content-negotiation.html.en b/docs/manual/content-negotiation.html.en
index 8403cb2733..6b4c6a6f1a 100644
--- a/docs/manual/content-negotiation.html.en
+++ b/docs/manual/content-negotiation.html.en
@@ -208,7 +208,7 @@
     depends on the setting of the <a
     href="mod/mod_mime.html#multiviewsmatch">MultiViewsMatch</a>
     directive.  This directive determines whether handlers, filters,
-    and other file types can participate in MultiViews
+    and other extension types can participate in MultiViews
     negotiation.</p>
 
     <h2>The Negotiation Methods</h2>
@@ -426,6 +426,10 @@
 
     <h3>Language Negotiation Exceptions</h3>
 
+    <p>New in Apache 2.0, some exceptions have been added to the
+    negotiation algorithm to allow graceful fallback when language
+    negotiation fails to find a match.</p>
+
     <p>When a client requests a page on your server, but the server
     cannot find a single page that matches the Accept-language sent by
     the browser, the server will return either a "No Acceptable
@@ -439,26 +443,28 @@
     href="mod_negotiation.html#languagepriority">LanguagePriority</a>
     directive.</p>
 
-    <p>The <code>ForceLanguagePriority</code> directive also causes
-    Apache to attempt to match language-subsets against their parent
-    language when no other match can be obtained.  For example, if a
-    client requests documents with the language <code>en-GB</code> for
-    British English, the server is not normally allowed by the
-    HTTP/1.1 standard to return a document that is marked as simply
+    <p>The server will also attempt to match language-subsets when no
+    other match can be found.  For example, if a client requests
+    documents with the language <code>en-GB</code> for British
+    English, the server is not normally allowed by the HTTP/1.1
+    standard to match that against a document that is marked as simply
     <code>en</code>.  (Note that it is almost surely a configuration
     error to include <code>en-GB</code> and not <code>en</code> in the
     Accept-Language header, since it is very unlikely that a reader
     understands British English, but doesn't understand English in
     general.  Unfortunately, many current clients have default
-    configurations that resemble this.)  With the
-    <code>ForceLanguagePriority</code> header, the server can be
-    configured to ignore the subset specification and match
-    <code>en-GB</code> against <code>en</code> documents.  But note
-    that if the client requests "en-GB; qs=0.9, fr; qs=0.8", and the
-    server has documents designated "en" and "fr", then the "fr"
-    document will be returned regardless of the
-    <code>ForceLanguagePriority</code> directive.  This is necessary
-    to maintain compliance with the HTTP/1.1 specification.</p>
+    configurations that resemble this.)  However, if no other language
+    match is possible and the server is about to return a "No
+    Acceptable Variants" error or fallback to the
+    <code>LanguagePriority</code>, the server will ignore the subset
+    specification and match <code>en-GB</code> against <code>en</code>
+    documents.  Implicitly, Apache will add the parent language to
+    the client's acceptable language list with a very low quality
+    value.  But note that if the client requests "en-GB; qs=0.9, fr;
+    qs=0.8", and the server has documents designated "en" and "fr",
+    then the "fr" document will be returned.  This is necessary to
+    maintain compliance with the HTTP/1.1 specification and to work
+    effectively with properly configured clients.</p>
 
 
     <h2>Extensions to Transparent Content Negotiation</h2>
diff --git a/docs/manual/mod/mod_negotiation.html.en b/docs/manual/mod/mod_negotiation.html.en
index 2235d574ca..f7de0488e5 100644
--- a/docs/manual/mod/mod_negotiation.html.en
+++ b/docs/manual/mod/mod_negotiation.html.en
@@ -142,7 +142,7 @@ cached by proxy servers</td></tr><tr><td nowrap="nowrap"><a href="directive-dict
     argument; it was turned on by the presence of the directive by
     itself.</p>
 <hr/><h2><a name="ForceLanguagePriority">ForceLanguagePriority</a> <a name="forcelanguagepriority">Directive</a></h2><table cellpadding="1" cellspacing="0" border="0" bgcolor="#cccccc"><tr><td><table bgcolor="#ffffff"><tr><td nowrap="nowrap"><strong>Description: </strong></td><td>Action to take if a single acceptable document is not 
-found</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Syntax" class="help">Syntax:</a></td><td>ForceLanguagePriority None|Prefer|Fallback [Prefer|Fallback]</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Default" class="help">Default:</a></td><td><code>ForceLanguagePriority None</code></td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Context" class="help">Context:</a></td><td>server config, virtual host, directory, .htaccess</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Override" class="help">Override:</a></td><td>FileInfo</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Status" class="help">Status:</a></td><td>Base</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Module" class="help">Module:</a></td><td>mod_negotiation</td></tr><tr><td nowrap="nowrap" align="left" valign="top"><a href="directive-dict.html#Compatibility" class="help">Compatibility:</a></td><td>Available in version 2.0.30 and later</td></tr></table></td></tr></table>
+found</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Syntax" class="help">Syntax:</a></td><td>ForceLanguagePriority None|Prefer|Fallback [Prefer|Fallback]</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Default" class="help">Default:</a></td><td><code>ForceLanguagePriority Prefer</code></td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Context" class="help">Context:</a></td><td>server config, virtual host, directory, .htaccess</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Override" class="help">Override:</a></td><td>FileInfo</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Status" class="help">Status:</a></td><td>Base</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Module" class="help">Module:</a></td><td>mod_negotiation</td></tr><tr><td nowrap="nowrap" align="left" valign="top"><a href="directive-dict.html#Compatibility" class="help">Compatibility:</a></td><td>Available in version 2.0.30 and later</td></tr></table></td></tr></table>
     <p>The <code class="directive">ForceLanguagePriority</code> directive uses
     the given <a href="#languagepriority" class="directive"><code class="directive">LanguagePriority</code></a> to satisfy
     negotation where the server could otherwise not return a single
diff --git a/docs/manual/mod/mod_negotiation.xml b/docs/manual/mod/mod_negotiation.xml
index a30ea4f0fa..a16372be99 100644
--- a/docs/manual/mod/mod_negotiation.xml
+++ b/docs/manual/mod/mod_negotiation.xml
@@ -180,7 +180,7 @@ cached by proxy servers</description>
 <description>Action to take if a single acceptable document is not 
 found</description>
 <syntax>ForceLanguagePriority None|Prefer|Fallback [Prefer|Fallback]</syntax>
-<default>ForceLanguagePriority None</default>
+<default>ForceLanguagePriority Prefer</default>
 <contextlist><context>server config</context>
 <context>virtual host</context>
 <context>directory</context>