Section 3.3.1.2 contains the ambiguous phrase "may not" in the second paragraph.

In the sentence:

"The types of the items in the typed value of a node may not be the same as the
type of the node itself"

replace the phrase "may not be the same as" by either "must differ from" or "may
differ from", whichever applies.

There are about three other places where the XDM specification uses the phrase
"may not". In these other cases the intelligent reader can work out which sense
is intended, but it would still be better to avoid the phrase.

Michael Kay