Dear James Clark,
The W3C XML Schema Working Group has spent the last several weeks
working through the comments received from the public on the
Candidate Recommendation (CR) of the XML Schema specification. We
thank you for the comments you made on our specification during
our CR comment period, and want to make sure you know that all
comments received during the CR comment period have been recorded
in our CR issues list (http://www.w3.org/2000/12/xmlschema-crcomments.html).
You raised the point registered as issue CR-17:
Title: Entities-and-notations: Remove notation type?
Description:
Declared NOTATIONs can be referred to from ENTITY declarations or from
attribute declarations. As things stand in the CR draft, any notation
referred to from an ENTITY declaration must be declared in the DTD; any
notation referred to from an attribute declaration must be declared in the
schema. (This last means that attribute types ENTITY and NOTATION behave
differently in a confusing way.)
Should this design be changed?
Resolution:
At its January 2001 meeting in London, the WG voted to open this as an
outstanding issue.
In discussion, it proved that there was no support for removing the
NOTATION type. Notations provide information about otherwise opaque
objects; they are not limited to entities, and there is no reason to remove
them from the XML Schema language simply because entities are not in the
language. It is true that processors which are both schema-aware and
DTD-aware will need to keep track of two distinct sets of notations;
notations do not differ, in this way, from many other constructs in schemas
and DTDs which have analogues in the other formalism.
The uniqueness constraint on notation names cannot be expressed by our type
derivation rules; this seems to require that NOTATION be a primitive, not a
derived type.
RESOLVED unanimously: to retain NOTATION.
RESOLVED unanimously: to make NOTATION a primitive, rather than a derived,
type.
It would be helpful to us to know whether you are satisfied with the
decision taken by the WG on this issue, or wish your dissent from the
WG's decision to be recorded for consideration by the Director of
the W3C.
Regards
Alex Milowski
XML Schema Working Group