Subordinate clauses are labeled CP or IP and their type is specified by an extended label.
The label CP is applied to all clauses which involve some operator or complementizer position: that-complements, indirect questions, relatives, free relatives, clefts, some adverbial clauses, degree clauses and comparative clauses.
The label IP is applied to infinitival clauses, gerund and participial clauses, as well as to small clauses.