I think the spec is clear, and no authors-intention clarifications are
relevant. To quote:
If the character reference begins with "&#x", the digits and letters
up to the terminating ";" provide a hexadecimal representation of the
character's value in ISO/IEC 10646
No reasonable interpretation of this could rule out any of ª or
ª or ª - I'm sure msxml will get around to fixing this. -Tim