W3C home > Mailing lists > Public > www-xml-schema-comments@w3.org > January to March 2001

Derivation by Extension: {content type} of {base type definition}

From: Helena Cavanagh <helena.cavanagh@usa.net>
Date: Wed Jan 24 09:18:45 2001
Message-ID: <20010124141843.17671.qmail@nwcst288.netaddress.usa.net>
To: www-xml-schema-comments@w3.org
Dear editors,

In Part 1, clause 4.3.3, tableau "Complex Type Definition with Complex Content
Schema Component", the definition of {content type} for the EXTENSION case
assumes that the {base type definition} has either a {content type} that is
empty (2.2) or that it has a particle (therefore is a pair of (content model,
mixed|element-only)) (2.3).

This is also implicit in "Constraint on Schemas: Derivation Valid
(Extension)", Clause 5.11, when it says:
"1.1.4 (...) and either the {content type} of the {base type definition} must
be empty or  
(...) the particle of the complex type definition must be a valid
extension of the {base type definition}'s particle, as defined in Particle
Valid (Extension) (5.10). "

Can't the {content type} of the {base type definition} be a simple type
definition? Isn't the following possible? (it is validated by XML Spy, though
that is no guarantee)

<xsd:schema xmlns:xsd="http://www.w3.org/2000/10/XMLSchema">

	<xsd:complexType name="aType">
			<xsd:extension base="xsd:string"/>
	<!-- {content type} is a simple-type definition (that of xsd:string) -->

	<xsd:complexType name="anotherType">
			<xsd:extension base="aType">
					<xsd:element name="subelem"/>


The {content type} of anotherType must be, according to (2.3) in the tableau
mentioned above:
"a pair of mixed or elementOnly (...) and a particle whose properties are as
{min occurs} 1 
{max occurs} 1 
{term} A model group whose {compositor} is sequence and whose {particles} are
_THE PARTICLE_ of the {content type} of the type definition resolved to by the
normalized value of the base [attribute] followed by the explicit content. "

The {content type} of aType has no 'particle', right?

Thank you,

Helena Cavanagh

Get free email and a permanent address at http://www.netaddress.com/?N=1
Received on Wednesday, 24 January 2001 09:18:45 UTC

This archive was generated by hypermail 2.3.1 : Wednesday, 7 January 2015 14:49:54 UTC