Re: Couldn't XML allow and ignore omitted tag minimization

dgd@cs.bu.edu (David Durand) wrote:

>   I am sympathetic to this, except for the SGML-imposed requirement that
> EMPTY tags must take minimization "- O" if they could be pure "noise"
> elements I wouldn't mind, but explaining that restriction in the context of
> "compatibility" is sure to be difficult.

By my interpretation of the standard, this is not actually
required, only recommended.  SGMLS agrees: it issues a warning
if it sees <!element foo - - EMPTY> in the DTD but it does flag
the document as non-conforming.  According to 7.3.1 and 11.2.2,
the parser doesn't even examine the tag omission parameters
for EMPTY elements or those with a non-#IMPLIED CONREF attribute.

(It would be nice to be able to turn this warning off in SGMLS/SP
though, especially for elements with CONREF attributes; I'd like
to be able to specify that the end-tag is always required if no
content reference attribute is supplied.  But that has nothing
to do with XML...)

--Joe English