What is an implementation supposed to do on this query?

    declare variable $thisVarIsNotRecognized external;
    $thisVarIsNotRecognized

In 4.14 Variable Declaration it is asserted that "If the variable declaration includes the keyword external, a value must be provided for the variable by the external environment before the query can be evaluated." Note the assertion("must") and the absence of an instruction on what to do if the assertion does not hold.

It seems XSL-T 2.0 handles this with a specific error code, XTDE0050(http://www.w3.org/TR/xslt20/#err-XTDE0050). This is actually what Saxon raises, which demonstrates the lack of coverage in the XQTS and probably also the specification.

I don't see how XPST0008 is supposed to be raised, since 4.14 Variable Declaration reads "A variable declaration adds the static type of a variable to the in-scope variables".

It seems that an error code is needed for when a lookup fails in the 'variable values'(dynamic context property) since the same paragraph says "and may also add a value for the variable to the variable values".

Therefore, with my current view on this, I suggest adding an error code that:

* Must be raised if a variable reference to an external variable does not have a corresponding value in the 'variable values'.
* May be raised statically when encountering an external variable declaration that the external environment doesn't have a value for.

The latter point ensure the 1) error can be consistently reported regardless of if the variable is used; 2) allow implementations to report the error without tracking use; and 3) still allows implementations to report it at runtime.


Frans