🚀 go-pugleaf

Michael Sperberg-McQueen writes:

>Eliot Kimber writes:
>
>>I think that use of the CONCUR feature is also not adequate because
>>the document can only be parsed against one active DTD at a time,
>>and thus the application must manage (and validate) the sharing
>>of data across elements in the concurrent DTDs.
>
>Does the standard say this?  It doesn't require a parser to parse more
>than one active doc type at a time, but does it require a parser to
>parse *no more* than one at a time?
>
>If it doesn't forbid parsing of multiple doc types simultaneously,
>then I think EK has oversimplified, and his statement should be
>recast to say "not all parsers claiming to support CONCUR will be
>able to do this in a useful way."

I think what the standard (and logic) say, is that you can only
parse against a single DTD at any given moment, although there's
no reason an interative parser couldn't interatively parse
against multiple DTDs over the same document fragment, but I don't
think that's any different, in effect.  The references I can find
in ISO 8879 for CONCUR (namely 7.1 Prolog), don't make it any
clearer for me.

My understanding of CONCUR is pretty weak, so I will defer
to Michael, who I know has studied CONCUR intensively.   My
main point was that CONCUR and the parser alone are not
sufficient to resolve or parse interactions between data
identified concurrently.  In other words, there is no
parser message that says "character string "x" is contained
by element A in DTD 1 and element B in DTD 2.  For it to
do so would go beyond the base task of parsing into
the application task of data analysis.  Of course, I could be
wrong.

Eliot Kimber                      Internet:  drmacro@ralvm13.vnet.ibm.com
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