In relatives where a 'pied-piped' preposition has not been expressed ('chopping relatives'), there are two ways of representing the null P. In Wochwel, Post Scriptum and Cordial, the interpreted preposition is inserted and codified inside (P (CODE {…})). In Tycho Brahe, P dominates a null preposition (P (0)).

(IP-MAT   (ADVP (ADV Ali))
          (ET-D-3S estava)
          (NP-SBJ   (D aquele)
                    (N peixe)
                    (, ,)
                    (CP-REL   (WPP-6   (P (CODE {a}))       <--------
                                       (WNP (WPRO que)))
                              (IP-SUB   (PP *T*-6)
                                        (NP-SBJ *pro*)
                                        (VB-D-3P botavam)
                                        (NP-ACC (N sal))
                                        (PP   (P para)
                                              (NP (N cima))))))
           (. .))
   [VPA06]

(IP-MAT   (CONJ E)
          (ADVP (ADV depois))
          (ADVP (ADV lá))
          (VB-D-3S foi)
          (NP-SBJ   (D o)
                    (N barco)
                    (CP-REL   (WPP-167   (P (CODE {em}))    <--------
                                         (WNP (WPRO que)))
                              (IP-SUB   (PP *T*-167)
                                        (NP-SBJ (PRO eu))
                                        (VB-D-1S andava))))
          (, ,))
   [VPA28]

([...]   (NP   (D-F a)
               (N casa)
               (CP-REL   (WPP-269   (P (CODE {em}))         <--------
                                    (WNP (WPRO que)))
                         (IP-SUB   (PP *T*-269)
                                   (NP-SBJ (PRO eles))
                                   (VB-P-3P vivem))))
                                   (ADV também))))
            [...])
   [VPA37]