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2.5.1 Predefined Schema Types "The schema types defined in [XQuery and XPath Data Model (XDM) 3.1] are summarized below." Using the correct URL: http://www.w3.org/TR/xpath-datamodel-31/#types-predefined, might alert proofers to XDM defining five (5) additional types, not six as listed here. #6 declares itself: "[Definition: xs:error is a simple type with no value space, defined in [XML Schema 1.1]." to not belong in the list.
xs:error is missing from XDM31. It is used in the XQuery and XPath specifications, it needs to be in the data model.
Noted also: Section 2.7.2 of XDM: (a) lists 5 "additional types" first defined in XDM rather than XSD, of which 3 have in fact been adopted by XSD 1.1. (b) omits types that are neither "primitive types" nor "additional types", of which xs:error is one example (others are xs:int, xs:NMTOKEN, etc) (c) omits another "additional type": xs:numeric
We decided that the types in the XS namespace could be classified as follows and that the section should be recast along these lines: The data model adopts the following types from [Schema 1.0 Part 2]: 19 primitive types... NN derived types... 3 built-in list types xs:NMTOKENS, IDREFS, ENTITIES It further defines the following types which were originally defined in XDM 1.0 and were subsequently adopted by XSD 1.1: xs:anyAtomicType xs:dayTimeDuration xs:yearMonthDuration In the case of a processor that "supports" XSD 1.1 the data model also includes: the new union type xs:error (a type with no instances) the new derived type xs:dateTimeStamp The following types, although they use the xs namespace, are defined here in XDM and not in XSD: xs:untypedAtomic xs:numeric, a union type whose members are xs:double, xs:float and xs:decimal
Noted also, F+O defines The type xs:numeric is defined as a union type whose member types are (in order) xs:double, xs:float, and xs:decimal. but this definition really ought to be in XDM.
XQuery / XPath do not currently say that only implementations that support XML Schema 1.1 need to support xs:error. This is not listed in this text: <quote> Whether the type system is based on [XML Schema 1.0] or [XML Schema 1.1]. An implementation that has based its type system on XML Schema 1.0 is not required to support the use of the xs:dateTimeStamp constructor or the use of xs:dateTimeStamp as TypeName in any expression. </quote>