Re: [xmlProfiles-29] TAG recommendation for work on subset of XML 1.1

>Message-ID: <>
>Date: Thu, 30 Jan 2003 16:45:53 -0500
>From: "Ian B. Jacobs" <>
>To: Liam Quin <>
>CC: Paul Grosso <>,, Michael Sperberg-McQueen <>
>Subject: [xmlProfiles-29] TAG recommendation for work on subset of XML 1.1

>One clear requirement of the subset is that it must exclude
>internal and external subsets (no <!DOCTYPE declaration is
>allowed). This requirement effectively removes DTDs from XML and
>consequently removes entities and notations.

I want to point out the existence of a number of standards in
the television domain that:

(1) disallow internal declaration subsets;
(2) require standalone="no";
(3) require a document type declaration, with a specifically
    enumerated set of public FPIs to be supported;

These standards include:

(1) ATSC DTV Application Software Environment (DASE) [1]
(2) DVB Multimedia Home Processing (MHP) Version 1.1 [2]
(3) SMPTE 363M Declarative Data Essence Level 1 [3]

The rationale for the restrictions adopted by these standards include:

* inability to request external entities in a broadcast only
  transport environment coupled with inadequate bandwidth for
  broadcast of DTDs;

* unacceptable complexity in mandating DTD declaration parsing
  document validation in small footprint, embedded devices
  (set-top boxes and integrated receiver decoder devices);

* need to support specific, limited set of document types; while
  allowing (but not requiring) validation based on pre-compiled

* need to identify content as to specific document type against
  which optional validation and application specific processing
  may occur;

As a result of this usage, I would have to conclude that complete
elimination of document type declaration is overkill, as it removes
valuable (FPI) information requiredby these standards and the
systems which employ them.

Glenn Adams


Received on Sunday, 16 February 2003 13:47:18 UTC