A projection WXP (including an interrogative, relative or exclamative element) is codified in wh-questions (CP-QUE), relatives (CP-REL) and free relatives (CP-FRL), cleft constructions (CP-CLF), comparative clauses (CP-CMP), in some adverbial clauses (CP-ADV) and in exclamatives (CP-EXL).

Typically WXP is coindexed with an empty category *T* representing wh-movement traces (but see bellow for exceptions). If applicable, dash tags indicating grammatical function or subcategory are assigned to wh-traces (and not to the WXP itself).

( (CP-QUE (WNP-1 (WPRO Que))
	  (IP-SUB (NP-ACC *T*-1)                                                                                                ☜ wh-question
		  (VB-R responderia)
		  (NP-SBJ (D aquelle) (ADJ-G grande) (N varão)))
	  (. ?))
  (TYCHO BRAHE; ID V_004,177.1072))

( (CP-QUE (WPP-1 (P A)                                                                                                                        ☜ wh-question
		 (NP (WPRO quem)))
	  (IP-IND (PP *T*-1)
		  (VB-D deu)
		  (NP-SBJ (D este) (N criminoso))
		  (NP-ACC (D-F essa)
			  (N soma)
			  (PP (P de)
			      (NP (N dinheiro)))))
	  (. ?))
  (POST SCRIPTUM; ID CARDS0094,.7))

( (IP-MAT (NP-SBJ (Q Todo)
		  (D o)
		  (N excesso)
		  (CP-REL (WNP-1 (WPRO que))                                 ☜ relative
			  (IP-SUB (NP-SBJ *T*-1)
				  (VB-SP altere)
				  (NP-ACC (D-F a) (N saúde)))))
	  (VB-P altera)
	  (NP-ACC (D-F a) (N beleza))
	  (. ;))
  (TYCHO BRAHE; ID A_004,76.989))

( (IP-MAT (NP-SBJ (CP-FRL (WNP-1 (WPRO Quem))                                                                        ☜ free relative
                          (IP-SUB (NP-SBJ *T*-1)
                                  (NP-ACC (CL o))
                                  (VB-P-3S compra)
                                  (Q muito))))
          (SR-P-3S é)
          (NP-PRD (D o)
                  (N espanhol))
          (. .))
  (CORDIAL-SIN; ID VPA10,14))

( (IP-MAT-SPE (CONJ e)
	      (NP-SBJ *exp*-2)
	      (NP-SBJ-2 (PRO eu))
	      (SR-D fuy)
	      (CP-CLF (WNP-1 (D-F a) (WPRO que))                                                                        ☜ cleft
		      (IP-SUB (NP-SBJ *T*-1)
			      (NP-DAT (CL vos))
			      (NP-ACC (CL o))
			      (VB-D mandey)
			      (ADVP (ADV là))))
	      (. .))
  (TYCHO BRAHE; ID C_002,139.100))

( (IP-MAT (CONJ e)
          (NP-SBJ *pro*)
          (VB-D-3P diziam)
          (. :)
          (CP-EXL-SPE (QT ")
                      (IP-IND (NP-SBJ (D O)
                                      (VB-AN amaldiçoado)
                                      (N carro))
                              (VB-P-3S come)
                              (NP-ACC (ADV-R mais)
                                      (N toucinho)
                                      (PP (P @de)
                                          (CP-CMP (WNP-1 (D @o)                                                        ☜ comparative
                                                         (WPRO que))
                                                  (IP-SUB (NP-MSR *T*-1)
                                                          (NP-SBJ (PRO eu)))))))
                      (QT ")
                      (. !)))
  (CORDIAL-SIN; ID AAL42,21))

( (IP-MAT (IP-MAT (NP-VOC (N Senhor))
		  (, ,)
		  (ADVP (ADV aí))
		  (VB-P vão)
		  (NP-SBJ (D-F-P as) (N-P testemunhas)))
	  (CONJP (CONJ e)
		 (IP-MAT (NP-SBJ (NPR VM))
			 (NP-ACC (CL as))
			 (VB-R ensinará)
			 (CP-ADV (WADVP-1 0)                                                                            ☜ adverbial
				 (C conforme)
				 (IP-SUB (ADVP *T*-1)
					 (NP-SBJ *exp*)
					 (SR-D foi)
					 (VB-AN dito)
					 (PP (P em@)
					     (NP (D-F @a) (N petição)))))))
	  [...]
  (POST SCRIPTUM; ID CARDS2191,.2))

( (IP-MAT (CONJ E)
	  (NP-SBJ *pro*)
	  (, ,)
	  (CP-ADV (C quando)
		  (IP-SUB (NP-SBJ *pro*)
			  (VB-D pode)
			  (IP-INF (VB fallar))))
	  (, ,)
	  (VB-D dise)
	  (. :)
	  (CP-EXL (DS -)
		  (NP-VOC (INTJ Ai) (N catiuuo))
		  (, ,)
		  (WNP-1 (WNP (WD que) (N dano))                                                                    ☜ exclamative
			 (CONJP (CONJ e)
				(WNP (WD que) (N coita))))
		  (IP-IND (NP-ACC *T*-1)
			  (NP-SBJ *exp*)
			  (ADVP (ADV aqui))
			  (HV-P a)))
	  (. !))
  (WOCHWEL; ID DSG346,.3))

WXPs can be null operators (WXP 0), as in the case of some cleft sentences, some comparative clauses and conformative clauses.

( (IP-MAT-SPE (DS -)
	      (NP-SBJ *exp*)
	      (ADVP (ADV Agora))
	      (SR-P é)
	      (CP-CLF (WADVP-1 0)
		      (C que)
		      (IP-SUB (ADVP *T*-1)
			      (NP-SBJ (PRO eu))
			      (ADVP (ADV já))
			      (NEG não)
			      (VB-P entendo))))
  (TYCHO BRAHE; ID G-004,0.688))

( (IP-MAT (NP-SBJ (PRO Ele))
          (SR-P-3S é)
          (ADJP-PRD (ADV-R mais)
                    (ADJ velho)
                    (CP-CMP (WADVP-1 0)
                            (C que)
                            (IP-SUB (ADVP-MSR *T*-1)
                                    (NP-SBJ (PRO eu)))))
          (, ,))
  (CORDIAL-SIN; ID VPA14,51))

( (IP-MAT (PP (P A@)
	      (NP (D @o)
		  (IP-INF (VB entardecer)
			  (PP (P d@)
			      (NP (D @aquele)
				  (N dia)
				  (PP (P de)
				      (NP (NPR Agosto))))))))
	  (, ,)
	  (NP-SBJ (D-F a)
		  (N mãe)
		  (PP (P de)
		      (NP (NPR Josefa))))
	  (, ,)
	  (CP-ADV (WADVP-1 0)
                  (C segundo)
		  (IP-SUB (ADVP *T*-1)
                          (NP-SBJ (D o) (N marido))
			  (VB-D contou)
			  (PP (P a@)
			      (NP (D @o) (N vigário)))
			  (PP (P n@)
			      (NP (D-F @a)
				  (N cangosta)
				  (PP (P d@)
				      (NP (D @o) (NPR Estêvão)))))))
	  (, ,)
	  (SR-D foi)
	  (VB-AN-F levada)
	  (PP (P em)
	      (NP (N-P braços)
		  (PP (P para)
		      (NP (D-F a) (N cama)))))
	  (. ;))
  (TYCHO BRAHE; ID B_005_PSD,28.766)) 

 In verbless exclamatives/questions (where no IP is projected) and in resumptive relatives (where there is no gap), the WXP is not coindexed with a trace:

( (CP-QUE (WPP (P Com)                                                                                                                            ☜ verbless question
	       (NP (D o) (WPRO quê)))
	  (. ?))
  (CORDIAL-SIN; ID PAL33,22))

( (CP-EXL-SPE (WNP (WD Que) (ADJ-G gram) (N destroição))                        ☜ verbless exclamative
	      (. !))
  (WOCHWEL; ID JAR50,.17))

( (IP-MAT (NP-SBJ (DEM Isso))
	  (SR-P-3S é)
	  (NP-PRD (D-UM-F uma)
		  (N coisa)
		  (CP-REL (WNP (WPRO que))                                                                                    ☜ resumptive relative
			  (IP-SUB (NP-SBJ *pro*)
				  (FP já)
				  (NP-DAT-RSP (CL lhe))
				  (VB-P-3P dão)
				  (NP-ACC (OUTRO outro) (N nome)))))
	  (. .))
  (CORDIAL-SIN; ID LVR18,100))