For compatibility

David Megginson david at
Fri Jul 17 15:58:28 BST 1998

Ron Bourret writes:

 > Section 2.5, "Comments", states that "For compatibility, the string "--" 
 > (double-hyphen) must not occur within comments."
 > I figured that this meant the spec authors were not totally happy
 > with this restriction, but they added it for SGML compatibility
 > reasons and that "--" really was not allowed in comments.  However,
 > both MSXML and Aelfred allow it.  XP does not.

 > Who is correct?  Does "for compatibility" mean the parser is not
 > required to support this if it is not interested in SGML
 > compatibility?  Is this something special about comments?

XP is correct.  This constraint is built directly into the grammatical

 [15] Comment ::= '<!--' ((Char - '-') | ('-' (Char - '-')))* '-->'

All the best,


David Megginson                 david at

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