[sv-bc] type compatibility for unions?

The type compatibility description seems to be missing the rules for packed
unions.
I think that rule 5 of type equivalence should be talking about packed
unions as well:
 
Packed arrays, packed structures, and built-in integral types are equivalent
if they contain the same number

of total bits, are either all 2-state or all 4-state, and are either all
signed or all unsigned. Note that if any bit of

a packed structure or union is 4-state, the entire structure or union is
considered 4-state.