Notation System Identifiers (was Re: Response to Simon St.L. on Entities v. XLL)

David Megginson ak117 at
Mon Dec 1 14:43:25 GMT 1997

Rick Jelliffe writes:

 > You can make up your own FPIs *now* for all MIME types using the following 
 > pattern.
 > <!NOTATION video-mpeg 
 >      PUBLIC "+//IDN 
 >      Multipurpose Internet Mail Extensions::video/mpeg//EN">

Yes, though this is not a well-formed XML notation declaration without
a system identifier.

On that point, I am still troubled about what to do with system
identifiers for notations.  WD-xml-971117 states that a system
identifier is "a URL, which may be used to retrieve the entity"
(sect.4.3.2), but we are not dealing with an entity here.  Later on,
when describing notations, the draft states that

  XML processors ... may additionally resolve the external identifier
  into the system identifier, file name, or other information needed
  to allow the application to call a processor for data in the
  notation described.


It would seem to me that a MIME type would make more sense than a URL
for the system identifier of notations, but that would introduce an
inconsistency into the external-identifier scheme.  I imagine that
this topic has already been beaten to death in the WG.

All the best,


David Megginson                 ak117 at
Microstar Software Ltd.         dmeggins at

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