This section defines the conformance criteria for an XQuery processor. In this section, the following terms are used to indicate the requirement levels defined in [RFC 2119]. [Definition: MUST means that the item is an absolute requirement of the specification.] [Definition: MAY means that an item is truly optional.] [Definition: SHOULD means that there may exist valid reasons in particular circumstances to ignore a particular item, but the full implications must be understood and carefully weighed before choosing a different course.]
An XQuery processor that claims to conform to this specification MUST include a claim of Minimal Conformance as defined in [9.1 Minimal Conformance]. In addition to a claim of Minimal Conformance, it MAY claim conformance to one or more optional features defined in [9.2 Optional Features].
[Definition: An XQuery processor MAY claim conformance to a subset of the XQuery Update 3.0 specification called "XQuery with Multiple Results" as defined in [9.3 XQuery with Multiple Results].] Implementations conforming to this subset but not to the Minimal Conformance may not claim to implement this specification.
Minimal Conformance to this specification MUST include all of the following items:
Minimal Conformance to [XQuery 3.0: An XML Query Language].
Support for everything specified in this document except those features specified in [9.2 Optional Features] to be optional and [E XML Syntax (XQueryX) for XQuery Update Facility 3.0]. If an implementation does not provide a given optional feature, it MUST implement any requirements specified in [9.2 Optional Features] for implementations that do not provide that feature.
A definition of every item specified to be implementation-defined, unless that item is part of an optional feature that is not supported by the implementation. A list of implementation-defined items can be found in [B Implementation-Defined Items].
Note:
Implementations are not required to define items specified to be implementation-dependent.
An implementation of XQuery that includes the Update Facility MAY also support the Optional Features of [XQuery 3.0: An XML Query Language]. These are Schema Import Feature, Schema Validation Feature, Full Axis Feature, Module Feature, and Serialization Feature.
A subset of the XQuery Update 3.0 specification called "XQuery with Multiple Results" is defined for the purposes of implementations only wishing to allow multiple results to be returned from an XQuery program. Implementations claiming conformance to the "XQuery with Multiple Results" subset MUST include all of the following items:
Minimal Conformance to [XQuery 3.0: An XML Query Language].
Support for the facilities described in the following sections of this document:
[4.2 Function Declaration]
excluding %updating
and %simple
annotations.
[4.3 Variable Declaration]
excluding %updating
and %simple
annotations.
Use of other types of XQuery Update 3.0 expression SHOULD result in an error [err:XPST0003]XP30.