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RE: Update on namespaces

From: Andrew Layman <andrewl@microsoft.com>
Date: Tue, 10 Jun 1997 16:08:20 -0700
Message-ID: <7BB61B44F197D011892800805FD4F792BE4320@RED-03-MSG.dns.microsoft.com>
To: w3c-sgml-wg@w3.org
I indeed think of types as equivalent to notations, as your mail points
out. Looking at notations, we see that they identify the format of an
external binary entity, and associate that format with a public
identifier.  That is, notations do specify data types, and within the
limits of XML public identifiers, notations are universally unique. 

Notations suffer from a few problems from our point of view, and that is
that they apply only to external entities, and types useful for routine
data processing as types such as INTEGER or DATE are not standardized.
The concepts are very similar, and maybe we can extend the idea of
notation to cover element contents.

However, notations are not the same as namespaces. Namespaces are not
data types. Namespaces are a general mechanism that allows any element
name (or by extension, any name) to be associated with a particular kind
of system literal, a URI, and thereby namespaces allow any name to be
made universally unique. Notations contain a mechanism by which
notations can be universally disambiguated; but it only works for
notations, it isn't general. Namespaces is a general mechanism that
universally disambiguates any name.

--Andrew Layman
   AndrewL@microsoft.com

> -----Original Message-----
> From:	len bullard [SMTP:cbullard@hiwaay.net]
> Sent:	Tuesday, June 10, 1997 3:11 PM
> To:	Andrew Layman
> Cc:	w3c-sgml-wg@w3.org
> Subject:	Re: Update on namespaces
> 
> Andrew Layman wrote:
> > 
> > As XML stands today,
> > their meaning is relative to the particular doctype and application
> > used.  Namespaces is a facility to pin down names exactly, in effect
> > saying "'birthday' as defined by organization x, 'type' as defined
> by
> > w3c, 'date' as defined by w3c."
> 
> That is, as I understand it, what <!NOTATION is for.  Why would this 
> not be the preferred way to indicate a formal public identifier in an 
> SGML subset?  Is NOTATION carrying baggage?  Is there an alternative?
> 
> len bullard
Received on Tuesday, 10 June 1997 19:08:35 EDT

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