There is very little difference between a token (or set of tokens) and the expressed value of an aspect. So '::UNWord::bits' is identical to '32'.

aspect-value   ::= aspect (value|type|label) (aspect identifier)...

Although a smart parser would not need the starting '::', the target of the Ocean syntax is to use as little forward scanning as possible. It is also much clearer for the programmer.

Caveat: the definition above is correct, but could also be specified as
  aspect (value|type|label) aspect identifier
and allow recursive resolution (as the result of an aspect is either a value, a type, or a label!)