Re: the return of the Public Identifier Question

> I was VP of Engineering at ArborText about 4 years ago.  Most bulk mail
> that currently gets addressed to:
> 	Paul Grosso
> 	VP of Engineering at ArborText
> (and a lot still does!) should and does get rerouted locally (by some
> effecient adminstrative folks) to Mike McEvoy who is the current VP of 
> Engineering.  It should not get sent to me, despite the fact that the
> "system id" of Paul Grosso is still a valid identifier.

That is exactly my point: the misalignment of public identifier target and
system identifier target is a mistake. The results should be unspecified.
If I send mail to Paul Grosso at Paul Prescod's address, I probably will not
get mail to Paul Grosso.

> > You can reliably continue this practice by deleting the system identifier. 
> No, the reader of a read-only document can do no such thing.

The author can delete the system identifier if their goal is to allow 
overriding. That was the scenario you described in your first message: the
author wants to allow overriding.

> Yes, one can add something like the OVERRIDE entry to the catalog.
> This is one way to implement my choice (g) which says to require 
> that there is some way for the user to specify which to try first
> (so that the user can specific that PUBLIC should be tried first).
> But I'm not going to be the one to suggest we complicate the XML catalog.

Nothing needs to be added to the catalog. Catalogs are by definition 
read/write*. This is the ultimate override. If an author wants to allow 
overriding, they should put in the public identifier and leave out the 
system identifier.

* If catalogs are not read/write, at least logically, then there is no way 
to override them, whether a system identifier is specified or not.

I am beginning to think it would be simplest to just require one or the
other. Providing both is useful when there is no reliable mechanism to
transmit a catalog, which represents a default lookup mechanism. But if we
specify a reliable catalog mechanism, what is the argument for allowing
both? It seems like it is just a feature designed to cause confusion and 

 Paul Prescod