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RE: Update on namespaces

From: Eve L. Maler <elm@arbortext.com>
Date: Wed, 18 Jun 1997 10:34:53 -0400
Message-Id: <>
To: w3c-sgml-wg@w3.org
As usual, in catching up with a pile of WG mail, I came across one old
message that I wanted to respond to.  I believe my point has been made
implicitly in further responses in this thread, but I thought it was worth
making explicitly:

At 04:08 PM 6/10/97 -0700, Andrew Layman wrote:
>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.

Notations do not apply only to external entities.  In 8879, a NOTATION
attribute on an element is meant to convey the notation in which the
element content is expressed.  XML has retained NOTATION attributes.

>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

If notation declarations are used to declare namespace ID prefixes, then
they do indeed universally disambiguate namespaces.   Of course,
namespaceID:gi is a novel way of *using* notation names.

Received on Wednesday, 18 June 1997 11:23:13 UTC

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