The XML spec in XML: missing tags

Eve L. Maler elm at
Wed Feb 25 00:30:26 GMT 1998

As the maintainer of the specification DTD, let me say thanks for your

At 11:49 AM 2/23/98 -0500, Michael Kay wrote:
>Some comments on the XML tagging in the BNF rules:
>- it is useful to have the non-terminals tagged, though the way in which it
>done is a little clumsy, since the internal identifier and the visible name
>of the non-terminal are necessarily in a one-to-one correspondence. The way
>it is done seems designed primarily to enable a particular translation to

Are you saying that it's clumsy because the element content is duplicated
in the attribute value?  Since the XML is transformed into HTML, it would
actually have been easier to let the content serve as the address (and be
stuffed into both the final <a> element content and its href attribute,
with "#" and "-nt" tacked on).  Alternatively, the element could have been
empty, and its attribute value both used as an address and rendered (with
some transformation that probably isn't worth doing...).  Either way,
nothing would be duplicated in the source.  However, it would make me a
little uncomfortable treating the same string as having two functions.

>- it is a shame that there is no tagging to distinguish terminal symbols
>from metasymbols, since this would enable nicer renditions of the rules,
>e.g. exploiting colour, without having to parse the BNF

I'll take this up with the other editors using the DTD.

>- it would seem more logical for each rule to have a single <rhs>, with any
><vc> and <wfc> constraints being embedded within the <rhs>, rather than
>these being separate elements interspersed among multiple <rhs> elements.

We had a lengthy discussion of whether our production markup should be more
semantic and less presentational.  It's so much work to make the markup
simulate the EBNF and to make the filters handle this, that we decided not
to go further in that direction.  I do agree that the production markup is
less than "pure" in this area.


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