Comments added.

1 files changed, 7 insertions, 5 deletions

diff --git a/etc/ETAGS.EBNF b/etc/ETAGS.EBNF
index a2b835af748..e548a11cbdd 100644
--- a/etc/ETAGS.EBNF
+++ b/etc/ETAGS.EBNF
@@ -1,11 +1,13 @@
 EBNF (Extended Backus Normal Form) description of the format of the tags
 file created by etags.c and interpreted by etags.el
+
+Productions created from current behaviour to aid extensions
 Francesco Potorti` <pot@gnu.org> 2002
 ================================================================
 
-FF ::= #x0c                                /* form feed */
+FF ::= #x0c                                /* tag section starter */
 
-LF ::= #x0a                                /* line feed */
+LF ::= #x0a                                /* line terminator */
 
 DEL ::= #x7f                               /* pattern terminator */
 
@@ -29,11 +31,11 @@ regularsec ::= filename "," [ unsint ] [ LF fileprop ] { LF tag }
 
 filename ::= regchar regstring             /* a file name */
 
-fileprop ::= DEL "(" regstring ")"
+fileprop ::= "(" regstring ")"             /* an elisp alist */
 
 tag ::= directtag | patterntag
 
-directtag ::= DEL realposition
+directtag ::= DEL realposition             /* no pattern */
 
 patterntag ::= pattern DEL [ tagname SOH ] position
 
@@ -41,6 +43,6 @@ pattern ::= regstring			   /* a tag pattern */
 
 tagname ::= regchar regstring              /* a tag name */
 
-position ::= realposition | ","
+position ::= realposition | ","            /* charpos,linepos */
 
 realposition ::= "," unsint | unsint "," | unsint "," unsint