enumeration and defaults

Tim Bray tbray at textuality.com
Tue Sep 14 17:17:39 BST 1999

At 10:06 AM 9/14/99 -0400, John Cowan wrote:
>And so I do.  I must say that I can see no possible reason for
>distinguishing, in an enumeration context, among not-present and
>null-string.  In a CDATA context, yes, because the zero-length
>string is a perfectly legitimate string distinct from logical null.

Well, except for detecting the not-present condition requires that your
software carry around the knowledge that this element foo could have had
a bar attribute but didn't, and treating that as equivalent to null-string.
Which is significant extra work.  Which leads me to think that legalizing
declarations like

<!ATTLIST foo bar (important|irrelevant|)>

would make a real difference.  Mind you, I don't hear mobs with pitchforks
in the streets crying for this... -Tim

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