RE: [emergency] Re: Circle and Polygon

["Winfield Wagner" <wwagner@crossflo.com>]

Claude Bullard:

You are correct on your analysis.  You have to forgive me on the fact
coming from the GJXDM world I have been brain washed into thinking XSD.
Before my GJXDM days and today I would use the attribute method for
solving the reference system identity situation. It is describer for the
domain of the element not a real world element in itself.  This has been
a very sticky point in GJXDM.  Many of elements are descriptive
variations that define a context of an element (how it is referenced in
a domain) rather than a real world element. 

Winfield J. Wagner


-----Original Message-----
From: Bullard, Claude L (Len) [mailto:len.bullard@intergraph.com] 
Sent: Friday, June 17, 2005 8:26 AM
To: Winfield Wagner; Aymond, Patti; Art Botterell; Emergency_Mgt_TC TC
Subject: RE: [emergency] Re: Circle and Polygon

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.