Not so fast...
It turns out that not all types are going to be allowed to have quasiforms and antiforms...
This means there are isotopic types and non-isotopic types.
WORD! is isotopic. PATH! is not.
There's a small quibble in the sense that WORD! is "partially isotopic"... only some symbols allow antiforms. But, it still affords all quasiforms. Calling it isotopic is fair game.
I don't know if isotopic? should be a function of values or datatypes. Accepting either would result in a lie.
>> isotopic? 'foo
== ~okay~ ; anti (words have quasi and anti forms)
>> isotopic? word!
== ~okay~ ; anti (again, words have quasi and anti forms)
>> word!
== &[word]
>> isotopic? &[word]
== ~okay~ ; anti (suggests that ~&[word]~ is a valid quasi/anti iform)
I don't think people will be asking if types or values are isotopic often. The biggest use is having an accelerated typeset built by the %types.r table available for the code that mechanically prevents the unwanted isotopes from being made.
An advantage of having it check the value instance instead of the type is that it can be used as a type constraint for things like quasi and anti on the parameters they take.