RE: [emergency] Re: Circle and Polygon

["Bullard, Claude L (Len)" <len.bullard@intergraph.com>]

Strictly speaking, you don't have to make it a base type 
because some systems don't process XSD, so an attribute's 
constraints in XML, per se, are the constraints of the 
application in the case of a well-formed instance or 
of a DTD given a valid instance under strict XML 
interpretation.

However, given XSD, that is a good way to do it 
and possibly useful.  XSD is somewhat controversial 
but I've no objection to its use here.

len


From: Winfield Wagner [mailto:wwagner@crossflo.com]

If the reference system is considered a identified form of measurement or a
distinct qualifier it should be an attribute.  It is metadata describing a
specific quality or context of the element. In order to do this you must
make a reference system element its own separate base type.  It can not
belong in the realm of type text or type code.  The reason is metadata
attributes should be connected to the type and not just to an element name
(reuse). It is not good practice to have single elements with their on
special metadata attributes.