The current version of the Head Filler Rule, which is a natural choice for a wh-question phrase, inherits from basic-filler-rule which restricts its second daughter to be QUE-empty:
basic-filler-phrase := binary-phrase & phrasal & [ SYNSEM [ LOCAL.CAT.VAL [ COMPS < >, SPR < > ], NON-LOCAL.SLASH 0-dlist ], ARGS < [ SYNSEM [ LOCAL #slash & local & [ CAT.VAL [ SUBJ olist, COMPS olist, SPR olist ], CTXT.ACTIVATED + ], NON-LOCAL.SLASH 0-dlist ] ], [ SYNSEM [ LOCAL.CAT [ VAL.COMPS olist ], NON-LOCAL [ SLASH 1-dlist & [ LIST [ FIRST #slash, REST < > & #last ], LAST #last ], QUE 0-dlist, REL 0-dlist ] ] ] > ].
The same constraint comes from yet another side, from the interrogative clause which in turn inherits from this:
basic-non-rel-clause := clause & head-compositional & [ SYNSEM.NON-LOCAL.REL 0-dlist, HEAD-DTR.SYNSEM [ LOCAL.CONT.HOOK [ INDEX #index, ICONS-KEY.IARG1 #index, CLAUSE-KEY #index ], NON-LOCAL [ QUE 0-dlist, REL 0-dlist ] ], C-CONT [ RELS <! !>, HCONS <! !> ] ].
However it seems like this precludes sentences of the Who did what type.
Should I remove the constraint on the matrix.tdl level or create new types?