Forwarded message 1
There are many in the ASN.1 world that want to move to XML Schema, and if I
am reading correctly, it seems you have said no to many.
When modeling by restriction, which is quite common, you have jumbled the
meaning of minOccurs. It means both that instances must contain data for
that element, and secondly that derived types by restriction must include
that element.
This is not logical. There are many circumstances when you want an
elemental data slot filled in a parent type instance, and then don't even
want the element in a derived child.
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The next issue I would like to address is about the level of
restriction. Can you explain this:
A complex type with an empty specification for {final} can be used as a
{base type definition} for other types derived by either of extension or
restriction; the explicit values extension, and restriction prevent further
derivations by extension and restriction respectively. If all values are
specified, then the complex type is said to be [Definition:] final: no
further derivations are possible.
Does it mean that a type which is derived by restriction and is
instantiable, can not be used as a base type for further restriction?
thank you,
Joseph Coyle MD, PhD Candidate
--
Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
W3C Fellow 1999--2001, part-time member of W3C Team
2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
URL: http://www.ltg.ed.ac.uk/~ht/