W3C home > Mailing lists > Public > xmlschema-dev@w3.org > June 2004

Re: Occurrence constraints

From: Henry S. Thompson <ht@inf.ed.ac.uk>
Date: Fri, 04 Jun 2004 10:14:31 +0100
To: "Xan Gregg" <Xan.Gregg@jmp.com>
Cc: "Keith Suderman" <keith@suderman.com>, <xmlschema-dev@w3.org>
Message-ID: <f5bpt8f8z2g.fsf@erasmus.inf.ed.ac.uk>

The Component Constraint you quote is just that, a constraint on
_components_ in _schemas_, and applies to the {max occurs} and {min
occurs} properties.

The XML Representation used in schema _documents_ allows the
_attributes_ maxOccurs and minOccurs to have value 0, but, as noted in
your other quote, this results in no component.

So e.g.

 <xs:sequence>
  <xs:element name="foo" type="baz" minOccurs="0" maxOccurs="0"/>
  <xs:element name="bar" type="xs:string"/>
 </xs:sequence>

may occur legally in a schema document, but the corresponding sequence
Particle component will contain only one Element Declaration
component.

Sorry for the confusion.

ht
-- 
 Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
                     Half-time member of W3C Team
    2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
            Fax: (44) 131 650-4587, e-mail: ht@inf.ed.ac.uk
                   URL: http://www.ltg.ed.ac.uk/~ht/
[mail really from me _always_ has this .sig -- mail without it is forged spam]
Received on Friday, 4 June 2004 05:14:46 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 11 January 2011 00:14:44 GMT