Null operator positions are included in cleft constructions, in comparative clauses and in certain adverbial clauses (as-clauses with a gap). Null operators are annotated in the first position inside CP and they are coindexed with a wh-trace.

( (IP-MAT (NP-SBJ *exp*-2)
	  (SR-D Foi)
	  (NP-2 (D-F a) (ADJ-F última) (N vez))
	  (CP-CLF (WNP-1 0)                                                                                                 ☜ cleft
		  (C que)
		  (IP-SUB (NP-ADV *T*-1)
			  (NP-SBJ *pro*)
			  (VB-D jantou)
			  (PP (P em)
			      (NP (N casa)
				  (PP (P de)
				      (NP (D-F a) (PRO$-F sua) (N sobrinha) (ADJ-F predileta))))))))
  (TYCHO BRAHE; ID A_003_PSD,46.688))

( (CP-EXL (IP-IND (NP-SBJ-1 *exp*)
		  (NP-1 (D O) (PRO$ meu) (N pai))
		  (SR-P-3S é)
		  (CP-CLF (WNP-2 0)                                                                                ☜ 'é que' inverted pseudocleft
			  (C que)
			  (IP-SUB (NP-SBJ *T*-2)
				  (SR-D-3S era)
				  (NP-PRD (D o) (N mestre)))))
	  (. !))
  (CORDIAL-SIN; ID VPA38,23))

( (IP-MAT (NP-SBJ *exp*)
	  (CP-CLF (WNP-1 0)                                                                                                  ☜ basic semipseudocleft
		  (IP-SUB (NP-ACC *T*-1)
			  (NP-SBJ (PRO Eles))
			  (VB-P-3P fazem)
			  (ADVP (ADV agora))))
	  (SR-P-3S é)
	  (NP-ACC (N-P caldeiradas))
	  (. .))
  (CORDIAL-SIN; ID CLC25,82))

( (IP-MAT (CONJ E)
	  (NP-SBJ *pro*)
	  (HV-P hei)
	  (PP (P de)
	      (IP-INF (VB fazer)
		      (IP-SMC (ADJP (ADJ-F verdadeira))
			      (NP-SBJ (D-F a) (N calhota)))))
	  (, ,)
	  (CP-ADV (C porque)
		  (IP-SUB (NP-SBJ *exp*)
			  (NEG não)
			  (HV-P há)
			  (NP-ACC (ADV-R mais)
				  (Q-F pouca)
				  (N vergonha)
				  (CP-CMP (WADVP-1 0)                                           ☜ comparative
					  (C que)
					  (IP-SUB (ADVP-MSR *T*-1)
						  (NP-SBJ (D-F a)
							  (PP (P de)
							      (NP (NPR VM)))))))))
	  (. .))
  (POST SCRIPTUM; ID CARDS1042,.6))

( (IP-MAT (CONJ E)
	  (NP-SBJ (DEM esto))
	  (NP-DAT (CL lhe))
	  (VB-D durou)
	  (, ,)
	  (CP-ADV (WADVP-1 0)                                            ☜ adverbial as-clause
		  (C segundo)
		  (IP-SUB (ADVP *T*-1)
			  (VB-P conta)
			  (NP-SBJ (D-F a) (N estorva))))
	  (, ,)
	  (PP (P em)
	      (NP (Q todo)
		  (D o)
		  (N tempo)
		  (CP-REL (WNP-2 (WPRO que))
			  (IP-SUB (NP-ADV *T*-2)
				  (NP-SBJ (PRO elle))
				  (VB-D reynou)))))
	  (. .))
  (WOChWEL; ID CGE363,.12))