An incompatible CData idea

David G. Durand david at
Mon Oct 27 17:24:15 GMT 1997

On Oct 27,  6:08pm, Jarle Stabell wrote:
> Instead of having to confront a DTD in order to find out whether an
> element(type) is CData or not, I feel it would be better if this info were
> explicit in the document instance.

It is. CDATA is not legal in XML DTDs at all (mostly because it's rather broken
-- any occurence of the "</" delimiters closes the element).

Instead, you must use CDATA marked sections:
<![ CDATA [ <contents> to </be> quoted ]]>

If you need the ]]> delimiter in the CDATA area, you must escape it via the use
of entities.

> proposal deleted.

> Pro:
> * Easy for the user, no need to remember/have DTD knowledge about
> CData/PCData when reading or writing a document without DTD-aware tools.

The marked section approach (SGML name for above ugly syntax) has all the
advantages except that it's ugly (and thus arguably not as easy as it could
be). But it is SGML compatible this way, and your proposal cannot be made
compatible, so is not suitable for XML.

> * Easy for the parser (for the same reason)

Ditto for both.

> Con:
> * Incompatible with SGML

CDATA marked sections don't have that problem, and so we chose them, despite
the uglier syntax.

David Durand                 dgd at| david at
Boston University Computer Science        | Dynamic Diagrams  |
                                          | MAPA: mapping for the WWW

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