A document model of the association of document contexts with XPath expressions and the URIs of expressions of enumerations of values. A context/value association file must not violate the W3C Schema XSD constraints expressed in the ContextValueAssociation.xsd associated with this version of the XML vocabulary. An application must report violations of document-level constraints. This identifies the governing query syntax used for addresses and expressions in the document. Absent this attribute an application is free to interpret the syntax in any manner. The document element of the document pointed to by this attribute must be <ContextValueAssociation> in the same namespace as the pointing document. The document contexts described in an including CVA file have higher detection priority than those found in an included CVA file. The document contexts described in an included CVA file have higher detection priority than those found in a previously-included CVA file. Expressed another way, the document contexts in the first included CVA file have the lowest detection priority. Any element found in a CVA file's <Identification> element has precedence over any like-named element that may or may not be present in the maquerading genericode file's or referenced genericode file's <Identification> element. Any element found in a masquerading genericode file's <Identification> element has precedence over any like-named element that may or may not be present in the referenced genericode file's <Identification> element, but lower precedence than any specified like-name element in the CVA file's <Identification> element. The key= attribute is required when the code list referenced by uri= has more than one key. The key= attribute, when specified, must be the value of a key identifier in the genericode file referenced by uri=. This query binding syntax address points to an instance-level metadata item from the perspective of the addressed context item. This query binding syntax address points to a descendant of <Identification> from the perspective of the <Identification> element. The contexts of a given CVA file are processed in descending priority based on order declared, such that an earlier described context has higher detection priority than those described after it (that is, the following sibling <Context> elements). Expressed another way, the document contexts within a given CVA file are processed in descending priority order of being declared. For a context's constraints to be considered fully satisfied, all of the referenced <ValueTest> expressions must evaluate to logical TRUE. At the same time the value must be present in any of the referenced <ValueList> value lists that have values and that qualify to be used in the presence of the given instance-level metadata described by any referenced <InstanceMetadataSet> sets. Referencing a <ValueList> that points to a value list without any values imposes no constraint on the context. An implementation that does not recognize any of the message use attributes shall use the first message element for value constraint violation reporting. An implementation that does recognize any of the message use attributes can choose any recognized message element for value constraint violation reporting. When there are no messages of any kind, or the selected message is empty, the application can use any wording in value constraint violation reporting. The token in the metadata= attribute points to an <InstanceMetadataSet> element. Each token in the values= attribute points to either a <ValueTest> element or a <ValueList> element. A message use URI standardized in the CVA specification (if any) shall, if recognized by an implementation, only represent the semantics described by the specification and not any custom semantics chosen by an application. All relative URI values in uri= attributes are resolved to the base URI of the uri= attribute, which is influenced by any ancestral xml:base= attributes that are present. The document element of the document pointed to by this attribute must be <CodeList> in an OASIS genericode namespace. All absolute URI attributes shall not have a relative URI value. Any measure of equivalence for a location URI is determined between users of this specification as this specification does not confer any identification semantics for these elements. A query address shall use an expression of the query binding syntax to address or query elements or attributes. The query binding syntax is implied by the queryBinding= attribute on <ContextValueAssociation>. Absent this attribute, there is no representation that the expression is in any particular syntax. A query boolean expression shall use an expression of the query binding syntax that returns a boolean value of true or false. The query binding syntax is implied by the queryBinding= attribute on <ContextValueAssociation>. Absent this attribute, there is no representation that the expression is in any particular syntax. A name token must lexically validate as would an un-prefixed element or attribute name.