s/this is,/that is,/

16 files changed, 28 insertions, 28 deletions

diff --git a/docs/CHANGES b/docs/CHANGES
index 85c154223..bc85f9d57 100644
--- a/docs/CHANGES
+++ b/docs/CHANGES
@@ -2424,7 +2424,7 @@ CHANGES BETWEEN 2.3.8 and 2.3.7
       is provided for x86 and ARM.  See FT_CONFIG_OPTION_INLINE_MULFIX
       and FT_CONFIG_OPTION_NO_ASSEMBLER (in ftoption.h) for more.
 
-    - The handling of `tricky' fonts  (this is, fonts which don't work
+    - The handling of `tricky' fonts  (that is, fonts which don't work
       with the  autohinter, needing the font  format's hinting engine)
       has been generalized and changed slightly:
 
@@ -2881,7 +2881,7 @@ CHANGES BETWEEN 2.2 and 2.1.10
 
   II. IMPORTANT CHANGES
 
-    - Version 2.2 no longer exposes its internals, this is, the header
+    - Version 2.2 no longer exposes its internals, that is, the header
       files  located in  the `include/freetype/internal'  directory of
       the source package are not  copied anymore by the `make install'
       command.  Consequently, a number of rogue clients which directly
diff --git a/docs/formats.txt b/docs/formats.txt
index 7a4bae09b..4b2f32eab 100644
--- a/docs/formats.txt
+++ b/docs/formats.txt
@@ -57,7 +57,7 @@ Notes
   (`*') in the table below.
 
   FreeType can  be configured to  support Mac  files (on older  Mac OS
-  versions, a `file' is stored as a data and a resource fork, this is,
+  versions, a `file' is stored as a data and a resource fork, that is,
   within two  separate data chunks).  If  a file can't be  opened as a
   font, FreeType then checks whether it  is a resource fork, trying to
   extract  the contained  font data  from  either a  `POST' or  `sfnt'
diff --git a/include/freetype/freetype.h b/include/freetype/freetype.h
index e855e6cb6..ec3fd31df 100644
--- a/include/freetype/freetype.h
+++ b/include/freetype/freetype.h
@@ -918,7 +918,7 @@ FT_BEGIN_HEADER
    *     If we have the third named instance of face~4, say, `face_index` is
    *     set to 0x00030004.
    *
-   *     Bit 31 is always zero (this is, `face_index` is always a positive
+   *     Bit 31 is always zero (that is, `face_index` is always a positive
    *     value).
    *
    *     [Since 2.9] Changing the design coordinates with
@@ -936,7 +936,7 @@ FT_BEGIN_HEADER
    *
    *     [Since 2.6.1] Bits 16-30 hold the number of named instances
    *     available for the current face if we have a GX or OpenType variation
-   *     (sub)font.  Bit 31 is always zero (this is, `style_flags` is always
+   *     (sub)font.  Bit 31 is always zero (that is, `style_flags` is always
    *     a positive value).  Note that a variation font has always at least
    *     one named instance, namely the default instance.
    *
@@ -1205,13 +1205,13 @@ FT_BEGIN_HEADER
    *     successfully; in all other cases you get an
    *     `FT_Err_Invalid_Argument` error.
    *
-   *     Note that CID-keyed fonts that are in an SFNT wrapper (this is, all
+   *     Note that CID-keyed fonts that are in an SFNT wrapper (that is, all
    *     OpenType/CFF fonts) don't have this flag set since the glyphs are
    *     accessed in the normal way (using contiguous indices); the
    *     'CID-ness' isn't visible to the application.
    *
    *   FT_FACE_FLAG_TRICKY ::
-   *     The face is 'tricky', this is, it always needs the font format's
+   *     The face is 'tricky', that is, it always needs the font format's
    *     native hinting engine to get a reasonable result.  A typical example
    *     is the old Chinese font `mingli.ttf` (but not `mingliu.ttc`) that
    *     uses TrueType bytecode instructions to move and scale all of its
@@ -2449,7 +2449,7 @@ FT_BEGIN_HEADER
    *   Each new face object created with this function also owns a default
    *   @FT_Size object, accessible as `face->size`.
    *
-   *   One @FT_Library instance can have multiple face objects, this is,
+   *   One @FT_Library instance can have multiple face objects, that is,
    *   @FT_Open_Face and its siblings can be called multiple times using the
    *   same `library` argument.
    *
@@ -2677,7 +2677,7 @@ FT_BEGIN_HEADER
    *   silently uses outlines if there is no bitmap for a given glyph index.
    *
    *   For GX and OpenType variation fonts, a bitmap strike makes sense only
-   *   if the default instance is active (this is, no glyph variation takes
+   *   if the default instance is active (that is, no glyph variation takes
    *   place); otherwise, FreeType simply ignores bitmap strikes.  The same
    *   is true for all named instances that are different from the default
    *   instance.
@@ -2974,7 +2974,7 @@ FT_BEGIN_HEADER
    *   glyph may be transformed.  See @FT_Set_Transform for the details.
    *
    *   For subsetted CID-keyed fonts, `FT_Err_Invalid_Argument` is returned
-   *   for invalid CID values (this is, for CID values that don't have a
+   *   for invalid CID values (that is, for CID values that don't have a
    *   corresponding glyph in the font).  See the discussion of the
    *   @FT_FACE_FLAG_CID_KEYED flag for more details.
    *
diff --git a/include/freetype/ftdriver.h b/include/freetype/ftdriver.h
index 59804ab1a..7af7465bc 100644
--- a/include/freetype/ftdriver.h
+++ b/include/freetype/ftdriver.h
@@ -134,7 +134,7 @@ FT_BEGIN_HEADER
    *   each being rounded to the nearest pixel edge, taking care of overshoot
    *   suppression at small sizes, stem darkening, and scaling.
    *
-   *   Hstems (this is, hint values defined in the font to help align
+   *   Hstems (that is, hint values defined in the font to help align
    *   horizontal features) that fall within a blue zone are said to be
    *   'captured' and are aligned to that zone.  Uncaptured stems are moved
    *   in one of four ways, top edge up or down, bottom edge up or down.
@@ -446,7 +446,7 @@ FT_BEGIN_HEADER
    *   at smaller sizes.
    *
    *   For the auto-hinter, stem-darkening is experimental currently and thus
-   *   switched off by default (this is, `no-stem-darkening` is set to TRUE
+   *   switched off by default (that is, `no-stem-darkening` is set to TRUE
    *   by default).  Total consistency with the CFF driver is not achieved
    *   right now because the emboldening method differs and glyphs must be
    *   scaled down on the Y-axis to keep outline points inside their
diff --git a/include/freetype/ftimage.h b/include/freetype/ftimage.h
index 738b515ed..6baa81256 100644
--- a/include/freetype/ftimage.h
+++ b/include/freetype/ftimage.h
@@ -862,7 +862,7 @@ FT_BEGIN_HEADER
    *   @FT_SpanFunc that takes the y~coordinate of the span as a parameter.
    *
    *   The anti-aliased rasterizer produces coverage values from 0 to 255,
-   *   this is, from completely transparent to completely opaque.
+   *   that is, from completely transparent to completely opaque.
    */
   typedef struct  FT_Span_
   {
diff --git a/include/freetype/ftoutln.h b/include/freetype/ftoutln.h
index 54434b25f..f9329ca40 100644
--- a/include/freetype/ftoutln.h
+++ b/include/freetype/ftoutln.h
@@ -118,7 +118,7 @@ FT_BEGIN_HEADER
    *   attachement.
    *
    *   Similarly, the function returns success for an empty outline also
-   *   (doing nothing, this is, not calling any emitter); if necessary, you
+   *   (doing nothing, that is, not calling any emitter); if necessary, you
    *   should filter this out, too.
    */
   FT_EXPORT( FT_Error )
diff --git a/src/autofit/afblue.dat b/src/autofit/afblue.dat
index b7efe8be6..8299baa25 100644
--- a/src/autofit/afblue.dat
+++ b/src/autofit/afblue.dat
@@ -89,7 +89,7 @@ AF_BLUE_STRING_ENUM AF_BLUE_STRINGS_ARRAY AF_BLUE_STRING_MAX_LEN:
     "ت ث ط ظ ك"
   // We don't necessarily have access to medial forms via Unicode in case
   // Arabic presentational forms are missing.  The only character that is
-  // guaranteed to have the same vertical position with joining (this is,
+  // guaranteed to have the same vertical position with joining (that is,
   // non-isolated) forms is U+0640, ARABIC TATWEEL, which must join both
   // round and flat curves.
   AF_BLUE_STRING_ARABIC_JOIN
diff --git a/src/autofit/aflatin.c b/src/autofit/aflatin.c
index 1082fee9a..d84579238 100644
--- a/src/autofit/aflatin.c
+++ b/src/autofit/aflatin.c
@@ -2038,7 +2038,7 @@
             max = seg2->max_coord;
 
           /* compute maximum coordinate difference of the two segments */
-          /* (this is, how much they overlap)                          */
+          /* (that is, how much they overlap)                          */
           len = max - min;
           if ( len >= len_threshold )
           {
diff --git a/src/autofit/afshaper.c b/src/autofit/afshaper.c
index 1b8b870e8..abc6f1d29 100644
--- a/src/autofit/afshaper.c
+++ b/src/autofit/afshaper.c
@@ -258,7 +258,7 @@
     /*
      * We now check whether we can construct blue zones, using glyphs
      * covered by the feature only.  In case there is not a single zone
-     * (this is, not a single character is covered), we skip this coverage.
+     * (that is, not a single character is covered), we skip this coverage.
      *
      */
     if ( style_class->coverage != AF_COVERAGE_DEFAULT )
@@ -313,9 +313,9 @@
      * hinted and usually rendered glyph.
      *
      * Consider the superscript feature of font `pala.ttf': Some of the
-     * glyphs are `real', this is, they have a zero vertical offset, but
+     * glyphs are `real', that is, they have a zero vertical offset, but
      * most of them are small caps glyphs shifted up to the superscript
-     * position (this is, the `sups' feature is present in both the GSUB and
+     * position (that is, the `sups' feature is present in both the GSUB and
      * GPOS tables).  The code for blue zones computation actually uses a
      * feature's y offset so that the `real' glyphs get correct hints.  But
      * later on it is impossible to decide whether a glyph index belongs to,
diff --git a/src/base/ftcalc.c b/src/base/ftcalc.c
index 997921883..442b08ddf 100644
--- a/src/base/ftcalc.c
+++ b/src/base/ftcalc.c
@@ -1061,7 +1061,7 @@
     /*                                                           */
     /* This approach has the advantage that the angle between    */
     /* `in' and `out' is not checked.  In case one of the two    */
-    /* vectors is `dominant', this is, much larger than the      */
+    /* vectors is `dominant', that is, much larger than the      */
     /* other vector, we thus always have a flat corner.          */
     /*                                                           */
     /*                hypotenuse                                 */
diff --git a/src/base/ftsystem.c b/src/base/ftsystem.c
index 98c046b83..61c99e363 100644
--- a/src/base/ftsystem.c
+++ b/src/base/ftsystem.c
@@ -206,7 +206,7 @@
    *     The number of bytes to read from the stream.
    *
    * @Return:
-   *   The number of bytes actually read.  If `count' is zero (this is,
+   *   The number of bytes actually read.  If `count' is zero (that is,
    *   the function is used for seeking), a non-zero return value
    *   indicates an error.
    */
diff --git a/src/cff/cffload.c b/src/cff/cffload.c
index f0e1977e2..fa2c29b28 100644
--- a/src/cff/cffload.c
+++ b/src/cff/cffload.c
@@ -400,7 +400,7 @@
 
   /* Allocate a table containing pointers to an index's elements. */
   /* The `pool' argument makes this function convert the index    */
-  /* entries to C-style strings (this is, null-terminated).       */
+  /* entries to C-style strings (that is, null-terminated).       */
   static FT_Error
   cff_index_get_pointers( CFF_Index   idx,
                           FT_Byte***  table,
diff --git a/src/cff/cffparse.c b/src/cff/cffparse.c
index a31f085d9..89a0263b7 100644
--- a/src/cff/cffparse.c
+++ b/src/cff/cffparse.c
@@ -622,7 +622,7 @@
 
       dict->has_font_matrix = TRUE;
 
-      /* We expect a well-formed font matrix, this is, the matrix elements */
+      /* We expect a well-formed font matrix, that is, the matrix elements */
       /* `xx' and `yy' are of approximately the same magnitude.  To avoid  */
       /* loss of precision, we use the magnitude of the largest matrix     */
       /* element to scale all other elements.  The scaling factor is then  */
diff --git a/src/pshinter/pshalgo.c b/src/pshinter/pshalgo.c
index a7f321291..4f622e1e4 100644
--- a/src/pshinter/pshalgo.c
+++ b/src/pshinter/pshalgo.c
@@ -516,7 +516,7 @@
             if ( !psh_hint_is_fitted( parent ) )
               psh_hint_align( parent, globals, dimension, glyph );
 
-            /* keep original relation between hints, this is, use the */
+            /* keep original relation between hints, that is, use the */
             /* scaled distance between the centers of the hints to    */
             /* compute the new position                               */
             par_org_center = parent->org_pos + ( parent->org_len >> 1 );
diff --git a/src/sdf/ftsdf.c b/src/sdf/ftsdf.c
index d8479af10..0a43e9be6 100644
--- a/src/sdf/ftsdf.c
+++ b/src/sdf/ftsdf.c
@@ -2371,7 +2371,7 @@
      *     ```
      *
      * (6) Our task is to find a value of `t` such that the above equation
-     *     `Q(t)` becomes zero, this is, the point-to-curve vector makes
+     *     `Q(t)` becomes zero, that is, the point-to-curve vector makes
      *     90~degrees with the curve.  We solve this with the Newton-Raphson
      *     method.
      *
@@ -2684,7 +2684,7 @@
      *     ```
      *
      * (6) Our task is to find a value of `t` such that the above equation
-     *     `Q(t)` becomes zero, this is, the point-to-curve vector makes
+     *     `Q(t)` becomes zero, that is, the point-to-curve vector makes
      *     90~degree with curve.  We solve this with the Newton-Raphson
      *     method.
      *
diff --git a/src/truetype/ttinterp.c b/src/truetype/ttinterp.c
index c6a6cde6b..3b7b21cca 100644
--- a/src/truetype/ttinterp.c
+++ b/src/truetype/ttinterp.c
@@ -7837,7 +7837,7 @@
         /* a variable number of arguments             */
 
         /* it is the job of the application to `activate' GX handling, */
-        /* this is, calling any of the GX API functions on the current */
+        /* that is, calling any of the GX API functions on the current */
         /* font to select a variation instance                         */
         if ( exc->face->blend )
           exc->new_top = exc->args + exc->face->blend->num_axis;
@@ -8397,7 +8397,7 @@
 #ifdef TT_CONFIG_OPTION_GX_VAR_SUPPORT
         case 0x91:
           /* it is the job of the application to `activate' GX handling, */
-          /* this is, calling any of the GX API functions on the current */
+          /* that is, calling any of the GX API functions on the current */
           /* font to select a variation instance                         */
           if ( exc->face->blend )
             Ins_GETVARIATION( exc, args );