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Re: Allowed PEReference usages

• To: xml-dev@l...
• Subject: Re: Allowed PEReference usages
• From: Arjun Ray <aray@n...>
• Date: Wed, 02 Jul 2003 17:10:50 +0000
• In-reply-to: <Law11-F113yF2mLEAH900039e24@h...>
• References: <Law11-F113yF2mLEAH900039e24@h...>

"Brett Kail" <junkaddr@h...> wrote:

| I'm generally unfamiliar with SGML, and I was unable to find a spec 
| online.  

Sadly, ISO copyright is in the way.  There is this:

 http://crism.maden.org/consulting/pub/sgmldefs.html

but it's missing the text of the standard.

| Where can I find one that discusses the PE rules of SGML?

Offhand I don't know of any, sorry.  You could try the search facility in
the Cover Pages.

|>| <!ENEITY %pe " ">
|>| <!ELEMENT%pe;e ANY>
|>
|> Permissible in SGML - maintains integral character of relevant parameters.
|> Probably okay in XML.
| 
| This one (and others you mark as "probably ok") make sense to me as well, 
| but is there anywhere we can go to get an authoritative answer?

I'd go with Section 4.4.8 "Included as PE" in the XML spec, especially
this:

: [...] the intent is to constrain the replacement text of parameter
: entities to contain an integral number of grammatical tokens in the DTD

and argue that zero is also an "integral number" :-)

Basically, PEs are a text substitution mechanism, so anything that doesn't
result in invalid text in the appropriate parsing context should be okay.

|> Note that the integral token restriction doesn't apply when using PErefs
|> to paste together the content of replacement text in what is effectively a
|> single parameter in a PE declaration.  (In fact, that is how you might
|> "construct" tokens if needed.)
| 
| Do you mean like so?
| 
| <!ENTITY % begin '<!ENTITY % value "str'>
| <!ENTITY % end 'ing">'>
| <!ENTITY % all '%begin;%end;'>
| %all;

Yes.  This "works".  As Bob Foster points out, %begin;%end; doesn't.

• References:
  • Re: Allowed PEReference usages
    • From: "Brett Kail" <junkaddr@h...>

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