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Re: Specifying scope of uniqueness in XML Schemas?

• From: ht@c... (Henry S. Thompson)
• To: Roger Costello <costello@m...>
• Date: 03 Jan 2000 17:29:52 +0000

Roger Costello <costello@m...> writes:

> In section 3.7 of the XML Schema spec it talks about the mechanism for
> indicating uniqueness (of elements, attributes, or combinations
> thereof).  It says that you can specify uniqueness within a region, or
> over the entire document:
> 
> "Constraints can be specified to have document-wide scope or to hold
> within the scope of particular elements."
> 
> Can someone explain to me how you indicate the scope of a constraint?  I
> am guessing that it is with the selector element, but I am not sure. 

Sorry this isn't clearer:  The scope is indicated by where the
declaration goes:  if I put a <key> element within an element
declaration for an element named 'foo', then the uniqueness and
ubiquity constraints obtain within each <foo>...</foo> in a document.

The <selector> tells you which elements WITHIN each <foo> must have keys.

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
	    Fax: (44) 131 650-4587, e-mail: ht@c...
		     URL: http://www.ltg.ed.ac.uk/~ht/

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• References:
  • null vs empty in XML Schemas
    • From: Roger Costello <costello@m...>
  • Specifying scope of uniqueness in XML Schemas?
    • From: Roger Costello <costello@m...>

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