\p{IsHighSurrogates}

F.1.1 rightly disallows \p{Cs} on the basis that surrogate characters "do
not occur at the level of the "character abstraction" that XML instance
documents operate on." But surely on the same basis IsHighSurrogates,
IsHighPrivateUseSurrogates and IsLowSurrogates should also be disallowed
within \p{} and \P{}.

James