Infinitival subject clauses, both preverbal and extraposed, are coindexed with a null expletive.

( (IP-MAT (CONJ Mas)
          (NP-SBJ-1 *exp*)
          (ADVP (ADV agora))
          (ADVP (ADV também))
          (SR-P-3S é)
          (ADJP-PRD (ADJ raro))
          (IP-INF-1 (VB caçar)
                    (NP-ACC (DEM isso)))
          (. .))
  (CORDIAL-SIN; ID VPA25,14))

( (IP-MAT (NP-SBJ-1 *exp*)
	  (PP-LFD (P A)
		  (NP (PRO mim)))
	  (Q muito)
	  (NP-DAT-RSP (CL me))
	  (VB-P admira)
	  (IP-INF-1 (NP-SBJ (NPR VM))
		    (TR ter)
		    (NP-ACC (N medo)
			    (PP (P de@)
				(NP (D-F @a) (N criada)))))
	  (. .))
  (POST SCRIPTUM; ID CARDS0179,.6))

(...)
(CP-ADV (C porque)
	(IP-SUB (NP-SBJ-5 *exp*)
		(IP-INF-5 (VB fazer)
			  (IP-SMC (NP-SBJ (NPR Castela))
				  (NP-ACC (N província)
					  (PP (P de)
					      (NP (NPR França))))))
		(NEG não)
		(VB-P cabe)
		(PP (P em)
		    (NP (Q-F tôda) (D-F a) (PRO$-F sua) (N vaidade))))
	(, ,)
	(CONJP (CONJ e)
	       (IP-SUB (NP-SBJ-6 *exp*)
		       (IP-INF-6 (VB dar-)
			         (NP-DAT (CL -lhe))
				 (NP-ACC (D-UM um)
					 (NPR Rei)
					 (CP-REL (WNP-7 (WPRO que))
						 (IP-SUB (NP-SBJ *T*-7)
							 (ADVP (ADV amanhã))
							 (HV-P há-)
							 (PP (P -de)
							 (IP-INF (SR ser)
								 (NP-ACC (N inimigo))))))))
				  (NEG não)
				  (VB-P vale)
				  (ADVP (ADV-R tanto)
					(CP-CMP (WADVP-8 0)
						(C como)
						(IP-SUB (ADVP *T*-8)
							(NP-SBJ (PRO$ seu) (N sossêgo))))))))))
	  (. .))
 (TYCHO BRAHE; ID B_008,48.429))
( (IP-MAT (CONJ mas)
	  (NP-SBJ-1 *exp*)
	  (IP-INF-1 (ET estar)
		    (PP (P a)
			(IP-INF (VB comprar)
				(NP-ACC (D-UM um) (N porco)))))
	  (, ,)
	  (PP (P @em)
	      (NP (D-F @a)
		  (N idade)
		  (CP-REL (WPP-2 (P em)
				 (NP (WPRO que)))
			  (IP-SUB (PP *T*-2)
				  (NP-SBJ *pro*)
				  (ET-P-1P estamos)))))
	  (, ,)
	  (FP já)
	  (NEG não)
	  (VB-P-3S dá)
	  (. .))
  (CORDIAL-SIN; ID LVR20,11))

Co-indexation between infinitival clauses and expletive subjects is extended to the cases in which, although the clause is interpreted as a subject, it is introduced by a preposition. Notice that also in this case the expletive subject is co-indexed with IP-INF and not with PP.

(IP-MAT (CONJ E)
        (NP-SBJ-1 *exp*)
        (PP (P por)
            (NP (DEM esto)))
        (VB-P cõvem)
        (PP (P de)
            (IP-INF-1 (NP-SBJ *pro*)
                      (NP-ACC (CL nos))
                      (VB-F defendermos)
                      (ADVP (Q muy)
                            (ADV ben))))
(...)
(WOCHWEL; ID CGE340,.41))

( (IP-MAT (CONJ E)
          (NP-SBJ-1 *exp*)
          (PP (P a@)
              (NP (D-P @os)
                  (N-P porteiros)))
          (VB-D prougue)
          (PP (P por)
              (IP-INF-1 (VB receber)
                        (NP-ACC (D o)
                                (N algo)
                                (PP (P de@)
                                    (NP (PRO @elle))))))
          (. .))
  (WOCHWEL; ID CGE345,.9))

As subject of small clauses, infinitival clauses are annotated under NP-SBJ or PP-SBJ.

( (IP-MAT (CONJ E)
	  (NP-SBJ *pro*)
	  (, ,)
	  (PP (P para)
	      (IP-INF (SR ser)
		      (ADJP (ADJ valioso))
		      (NP-SBJ (D o) (PRO$ nosso) (N contrato))))
	  (, ,)
	  (NEG não)
	  (VB-P julgo)
	  (IP-SMC (ADJP (ADJ necessário))
		  (NP-SBJ (IP-INF (SR ser)
			          (VB-AN-F feita)
			          (NP-SBJ (D-F a) (N procuração))
			          (PP (P por)
				      (NP (N tabelião)))
			          (, ,)
			          (CP-ADV (WADVP-1 0)
				          (C como)
				          (IP-SUB (ADVP *T*-1)
					          (NP-SBJ (PRO tu))
					          (VB-P dizes))))))
	  (. .))
  (POST SCRIPTUM; ID CARDS0055,.3))

( (IP-MAT (NP-LFD-1 (DEM Isto))
	  (VB-P posso)
	  (NP-SBJ (PRO eu))
	  (IP-INF (NP-ACC *ICH*-1)
		  (VB dizer)
		  (PP (P de@)
		      (NP (D-F @a)
			  (N enchente)
			  (PP (P de@)
			      (NP (D-P @os) (PRO$-P meus) (N-P pesares))))))
	  (, ,)
	  (IP-GER (TR-G tendo)
		  (ADVP (ADV agora))
		  (IP-SMC (PP (P por)
			      (ADJP (ADJ-R-G maior)))
			  (NP-SBJ (IP-INF (NEG não)
				          (VB achar)
				          (NP-ACC (D o)
					          (N patrocínio)
					          (PP (P de)
						      (NP (NPR VSa))))))))
	  (. .))
  (POST SCRIPTUM; ID CARDS1081,.2))

( (IP-MAT (CONJ Mas)
	  (NP-SBJ (D o) (NPR Senhor) (NPR Deus))
	  (TR-D teve)
	  (IP-SMC (PP (P por)
		      (NP (N bẽ))))
		  (PP-SBJ (P de)
		          (IP-INF (NP-SBJ (Q-P todos))
				  (SR-F seerẽ)
				  (VB-PP vencidos)
				  (PP (P a)
				      (NP (Q-F pouca)
				   	  (PP (P d’)
          				      (NP (N ora))))))))
          (...)
  (WOCHWEL; ID CGE329,.38))