Question: Physics[Vectors] vector type

Is there  a specific type name for vectors in Physics[Vectors]?  Specifically, Let's say we want to write a proc whose argument is expected to be a (Physics) Vector, as in  these (trivial) demos:

with(Physics[Vectors]);

f := proc(a_::???)
    return a_ . a_;
end proc:

g := proc(a_::???, b_::???)
    return a_ &x b_;
end proc:

What do we put in place of "???".

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