- From: Joe English <jenglish@crl.com>
- Date: Wed, 04 Jun 1997 11:17:51 -0700
- To: w3c-sgml-wg@w3.org
Eve L. Maler <elm@arbortext.com> wrote: > At 12:31 PM 6/3/97 -0700, Joe English wrote: > ... > >CDATA and RCDATA declared content can be replaced with (#PCDATA), > >as this is semantically (though not syntactically) equivalent. > > Since XML has no inclusions, I think (#PCDATA) results in a model whose > instances have the same constraints as RCDATA models. Right? CDATA is > another story. Depends on how you look at it I suppose... Neither ESIS nor the SGML grove plan distinguish elements with declared content from those with mixed or element content (unless you look up the element type declaration in prlgabs1), which is why I feel that they're semantically equivalent. That inclusions cannot appear in RCDATA declared content nor data entity references in CDATA declared content I consider to be an incidental consequence of the parsing process; that is, there's no semantic restriction against them, it's just that the parser will refuse to recognize them should they appear. In any case, replacing CDATA declared content with (#PCDATA) yields a superset language, and changing RCDATA declared content to (#PCDATA) yields an equivalent language (modulo delimiter recognition modes), like Eve said. BTW, in my previous message I left out: If an element has a #CONREF attribute, and its content model does not allow empty content (i.e., is not "inherently optional"), you have to add an OPT occurrence indicator to make this possible. (I also completely forgot about entity declarations, but Eve's message covered those pretty thoroughly.) --Joe English jenglish@crl.com
Received on Wednesday, 4 June 1997 14:31:34 UTC