UMLR — History Pseudostates should be allowed for top-level regions

The specification says:

a deep/shallow History Pseudostate can only be defined for composite States

There is no corresponding constraint.

And the PSSM-specification allows them:

If the history Pseudostate is owned by a top-level Region [...]

And I think it is useful when the statemachine is used as a submachine.

Therefore, I suggest deleting the sentence.