Comments improved.

diff --git a/src/m17n-flt.h b/src/m17n-flt.h
index f1454aa..b002939 100644 (file)
--- a/src/m17n-flt.h
+++ b/src/m17n-flt.h
@@ -241,14 +241,18 @@ typedef struct
 
     The type #MFLTOtfSpec is the structure that contains information
     about the GSUB and GPOS features of a specific script and language
-    system to be applied to a glyph sequence.  */
+    system.  The information is used to select which features to
+    apply to a glyph string, or to check if a specific FLT is usable
+    for a specific font.  */
 
 /***ja
     @brief GSUB ¤ª¤è¤Ó GPOS OpenType ¥Æ¡¼¥Ö¥ë¤Î»ÅÍͤΤ¿¤á¤Î·¿.
 
     ·¿ #MFLTOtfSpec ¤Ï¡¢GSUB ¤ª¤è¤Ó GPOS¥Õ¥£¡¼¥Á¥ã¡¼¤Î¾ðÊó¤ò³ÊǼ¤¹¤ë¤¿
     ¤á¤Î¹½Â¤ÂΤǤ¢¤ë¡£¤³¤ì¤é¥Õ¥£¡¼¥Á¥ã¡¼¤ÏÆÃÄê¤Î¥¹¥¯¥ê¥×¥È¤ª¤è¤Ó¸À¸ì¥·
-    ¥¹¥Æ¥à¤Î¤â¤Î¤Ç¤¢¤ê¡¢¥°¥ê¥ÕÎó¤ËŬÍѤµ¤ì¤ë¡£  */
+    ¥¹¥Æ¥à¤Î¤â¤Î¤Ç¤¢¤ë¡£¤³¤Î¾ðÊó¤Ï¡¢¤É¤Î¥Õ¥£¡¼¥Á¥ã¡¼¤ò¥°¥ê¥ÕÎó¤ËŬÍѤ¹
+    ¤ë¤«¡¢¤¢¤ë¤¤¤ÏÆÃÄê¤Î FLT ¤¬ÆÃÄê¤Î¥Õ¥©¥ó¥È¤ËÂФ·¤ÆÍ­¸ú¤«¤É¤¦¤«¤Î·èÄê
+    ¤Ë»ÈÍѤµ¤ì¤ë¡£  */
 
 typedef struct
 {
@@ -265,14 +269,40 @@ typedef struct
   /* @} */
 
   /***en Array of GSUB (1st element) and GPOS (2nd element) feature
-      tag arrays.  Each array is terminated by 0.  If the first
-      element is 0xFFFFFFFF, apply all the features except those that
-      appear in the following elements.  It may be NULL if there are
-      no features.  */
+      tag arrays.  Each array is terminated by 0.  It may be NULL if
+      there is no feature to specify.
+
+      (1) The case of using this information for selecting which
+      features to apply to a glyph string.  If the array is NULL,
+      apply no feature.  If the first element is 0, apply all
+      available features.  If the first element is 0xFFFFFFFF, apply
+      all available features except for what appear in the second and
+      following elements.  Otherwise, apply all listed features.
+
+      (1) The case of using this information for checking if a a font
+      can be drived by a specific FLT.  If the array is NULL, the font
+      should not have any features.  If the first elements is 0, don't
+      check the font.  Otherwize, the font should have all features
+      before 0xFFFFFFFF element (if any) and should not have any
+      features after that element.  */
   /***ja GSUB ¥Õ¥£¡¼¥Á¥ã¡¼¥¿¥°¤ÎÇÛÎó¤òÂè1Í×ÁÇ¡¢GPOS ¥Õ¥£¡¼¥Á¥ã¡¼¥¿¥°¤Î
-      ÇÛÎó¤òÂè2Í×ÁǤȤ¹¤ëÇÛÎó¡£³ÆÇÛÎó¤ÎËöÈø¤Ï0¤Ç¼¨¤µ¤ì¤ë¡£¤â¤·ºÇ½é¤ÎÍ×
-      ÁǤ¬ 0xFFFFFFFF¤Ê¤é¤Ð¡¢°Ê¹ß¤ÎÍ×ÁǤȤ·¤Æ¸½¤ï¤ì¤ë¥Õ¥£¥Á¥ã¡¼°Ê³°¤Î¤¹
-      ¤Ù¤Æ¤òŬÍѤ¹¤ë¡£¥Õ¥£¡¼¥Á¥ã¡¼¤¬1¤Ä¤â¤Ê¤¤¾ì¹ç¤Ï NULL ¤Ç¤â¤è¤¤¡£ */
+      ÇÛÎó¤òÂè2Í×ÁǤȤ¹¤ëÇÛÎó¡£³ÆÇÛÎó¤ÎËöÈø¤Ï0¤Ç¼¨¤µ¤ì¤ë¡£¥Õ¥£¡¼¥Á¥ã¡¼
+      ¤Î»ØÄ꤬1¤Ä¤â¤Ê¤¤¾ì¹ç¤Ï¤³¤ÎÇÛÎó¤ÎÍ×ÁÇ¤Ï NULL ¤Ç¤â¤è¤¤¡£
+
+      (1) ¤³¤Î¾ðÊ󤬥°¥ê¥ÕÎó¤ËŬÍѤ¹¤Ù¤­¥Õ¥£¡¼¥Á¥ã¡¼¤ÎÁªÂò¤Ë»È¤ï¤ì¤ë¾ì
+      ¹ç¡£¤â¤·ÇÛÎ󼫿Ȥ¬NULL¤Ê¤é¡¢¤É¤Î¥Õ¥£¡¼¥Á¥ã¡¼¤âŬÍѤ·¤Ê¤¤¡£¤â¤·ºÇ
+      ½é¤ÎÍ×ÁǤ¬0¤Ê¤é¡¢Å¬ÍѲÄǽ¤Ê¤¹¤Ù¤Æ¤Î¥Õ¥£¡¼¥Á¥ã¡¼¤òŬÍѤ¹¤ë¡£¤â¤·ºÇ
+      ½é¤ÎÍ×ÁǤ¬ 0xFFFFFFFF ¤Ê¤é¡¢£²ÈÖÌܰʹߤΥե£¡¼¥Á¥ã¡¼¤ò½ü¤¯¤¹¤Ù¤Æ
+      ¤ÎŬÍѲÄǽ¤Ê¥Õ¥£¡¼¥Á¥ã¡¼¤òŬÍѤ¹¤ë¡£¤½¤ì°Ê³°¤Î¾ì¹ç¥ê¥¹¥È¤µ¤ì¤¿¤¹
+      ¤Ù¤Æ¤Î¥Õ¥£¡¼¥Á¥ã¡¼¤òŬÍѤ¹¤ë¡£
+
+      (2) ¤³¤Î¾ðÊó¤¬ÆÃÄê¤Î FLT ¤¬ÆÃÄê¤Î¥Õ¥©¥ó¥È¤ËÍ­¸ú¤«¤É¤¦¤«¤Î·èÄê¤Ë»È
+      ¤ï¤ì¤ë¾ì¹ç¡£¤â¤·ÇÛÎ󼫿Ȥ¬NULL¤Ê¤é¡¢¥Õ¥©¥ó¥È¤Ï¥Õ¥£¡¼¥Á¥ã¡¼¤ò°ì¤Ä
+      ¤â»ý¤Ã¤Æ¤¤¤Æ¤Ï¤¤¤±¤Ê¤¤¡£¤â¤·ºÇ½é¤ÎÍ×ÁǤ¬0¤Ê¤é¡¢¤É¤ó¤Ê¥Õ¥©¥ó¥È¤Ç¤â
+      Îɤ¤¡£¤â¤·ºÇ½é¤ÎÍ×ÁǤ¬0xFFFFFFFF¤Ê¤é¡¢¥Õ¥©¥ó¥È¤Ï£²ÈÖÌܤÎÍ×Áǰʹß
+      ¤Î¥Õ¥©¥ó¥È¤ò»ý¤Ã¤Æ¤¤¤Æ¤Ï¤¤¤±¤Ê¤¤¡£¤½¤ì°Ê³°¤Î¾ì¹ç¡¢¥Õ¥©¥ó¥È¤Ï
+      0xFFFFFFFF °ÊÁ°¤Î¤¹¤Ù¤Æ¤Î¥Õ¥£¡¼¥Á¥ã¡¼¤ò»ý¤Á¡¢¤«¤Ä 0xFFFFFFFF °Ê¹ß
+      ¤Î¥Õ¥£¡¼¥Á¥ã¡¼¤Ï°ì¤Ä¤â»ý¤Ã¤Æ¤¤¤Æ¤Ï¤¤¤±¤Ê¤¤¡£*/
   unsigned int *features[2];
 } MFLTOtfSpec;