§ 14.1/4 of the C++03 Standard allows having pointers to member as a template parameter:
A non-type template-parameter shall have one of the following (optionally cv-qualified) types:
- integral or enumeration type,
- pointer to object or pointer to function,
- reference to object or reference to function,
- pointer to member.
Correspondingly, per § 14.3.2/1:
A template-argument for a non-type, non-template template-parameter shall be one of:
- an integral constant-expression of integral or enumeration type; or
- the name of a non-type template-parameter; or
- the address of an object or function with external linkage, including function templates and function template-ids but excluding non-static class members, expressed as & id-expression where the & is optional if the name refers to a function or array, or if the corresponding template-parameter is a reference; or
- a pointer to member expressed as described in 5.3.1.
Thus, non-type template parameters can be pointers to member. There are some limitations which apply to template specialization, but they don't seem to apply in this case.