The following items in this specification are implementation-defined:
The version of Unicode that is used to construct expressions.
The implicit timezone.
The circumstances in which warnings are raised, and the ways in which warnings are handled.
The method by which errors are reported to the external processing environment.
Which version of XML and XML Names (e.g. [XML 1.0] and [XML Names] or [XML 1.1] and [XML Names 1.1]) and which version of XML Schema (e.g. [XML Schema 1.0] or [XML Schema 1.1]) is used for the definitions of primitives such as characters and names, and for the definitions of operations such as normalization of line endings and normalization of whitespace in attribute values. It is recommended that the latest applicable version be used (even if it is published later than this specification).
How XDM instances are created from sources other than an Infoset or PSVI.
Whether the implementation supports the namespace axis.
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
or xs:error
as TypeName in any expression.
The signatures of functions provided by the implementation or via an implementation-defined API (see 2.2.1 Static Context).
Any environment variables provided by the implementation.
Any rules used for static typing (see 2.3.3.1 Static Analysis Phase).
Any serialization parameters provided by the implementation
What error, if any, is returned if an external function's implementation does not return the declared result type (see 2.3.4 Consistency Constraints).
Note:
Additional implementation-defined items are listed in [XQuery and XPath Data Model (XDM) 3.1] and [XQuery and XPath Functions and Operators 4.0].