- From: Yuri de Wit <yuri.dewit@metaserver.com>
- Date: Mon, 29 Apr 2002 12:52:29 -0400 (EDT)
- To: "'xmlschema-dev@w3.org'" <xmlschema-dev@w3.org>
- Message-ID: <D4DC61068C33D51186A700306E061976A42DF2@bianca.metaserver.com>
The XML Schema specification constrains how groups may be used in circular dependencies. My understanding is that the circularity constraint applies only to model groups and nested items and not to top level types or elements. For instance, consider the following XML Schema. Is it a valid XML Schema with a recursive type reference? I can see problems if minOccurs=0 is not specified, but is it a valid schema based on the XML Schema spec? Is it valid? <complexType name="error"> <sequence> <element name="name" type="xsd:string"/> <element name="code" type="xsd:string" /> <element name="message" type="xsd:string" /> <element name="description" type="xsd:string" minOccurs="0"/> <element name="source" type="xsd:string" minOccurs="0"/> <element name="content" type="xsd:base64Binary" minOccurs="0"/> <element name="error" type="ms:error" minOccurs="0"/> </sequence> </complexType> Here is the part of the spec dealing with constraints on Model Groups ---------------------------------------------------------------------------- ----- 3.8.6 Constraints on Model Group Schema Components All model groups (see Model Groups (§3.8)) must satisfy the following constraints. Schema Component Constraint: Model Group Correct All of the following must be true: 1 The values of the properties of a model group must be as described in the property tableau in The Model Group Schema Component (§3.8.1), modulo the impact of Missing Sub-components (§5.3). 2 Circular groups are disallowed. That is, within the {particles} of a group there must not be at any depth a particle whose {term} is the group itself. -------------------------------------------------------
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Received on Wednesday, 1 May 2002 04:53:49 UTC