ACTION A-641-13

ACTION A-641-13 (bug 29571) on Jonathan and Tim to agree a Note to
add to the spec to make it clear to readers that when T is a list type, T(x)
cast as T will typically fail.


I suggest the following text



NOTE:

As a consequence of the rules for casting (Section 19 Casting FO31), for an expression E and type T, where
   
1. T is a list type, or T is a union type of which a list type is in its transitive membership, and

2. (E instance of L) eq true

then

E castable as L

is false.  For example xs:NMTOKENS("a b c") castable as XS:NMTOKENS is false.

Furthermore, if L is a list type with a minimum length facet of zero, () castable as L is false.


Perhaps a similar note should be added to cover E cast as L.