----- Original Message -----
From: Peter Flynn <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, July 09, 1999 04:28
Subject: Re: Notations/Entities (WAS: Re: Lookup Tables and DTDs)
> You could use a SYSTEM identifier; I used a PUBLIC because I generally do
> with SGML. With SGML, I believe it would attempt to resolve the SYSTEM
> to a resource, wouldn't it?
Some software does: some doesn't. The cause is that SGML doesn't
specify which identifier software should "prefer", PUBLIC or SYSTEM.
There is some software which will look at one and ignore the other, and
some which does the reverse. In fact, most software does the "wrong"
thing when both PUBLIC and SYSTEM are supplied, in not testing both for
resolution but grabbing the first one that resolves, or trying one only
and if that doesn't work, issuing an error message without trying the
And in the absence of a catalog, a lot of software has some really
curious ideas about where to look for file entities and what they might
be called. One program will only check files that end with ".ent";
another only looks in /usr/local/lib/sgml/; yet another tries the
instance directory and nowhere else, etc etc.
I use PUBLIC only for SGML because the people I exchange files with
all use catalogs and all know what to do. I use both PUBLIC and SYSTEM
identifiers on XML because SYSTEM is required but I believe it is more
meaningful and useful (to anyone who actually inspects the file) if
they can see the claim to identification implied by a Formal Public