<p>
The type <code>T</code> in a term of the form <code>T</code> or <code>~T</code> cannot
be a <a href="#Type_parameter_declarations">type parameter</a>, and the type sets of all
non-interface terms must be pairwise disjoint (the pairwise intersection of the type sets must be empty).
Given a type parameter <code>P</code>:
</p>

<pre>
interface {
	P                // illegal: P is a type parameter