The Free On-line Dictionary of Computing (30 December 2018):

P-TAC

   Parallel Three Address Code.

   Kid is a refinement of P-TAC, used as an intermediate
   language for Id.

   ["P-TAC: A Parallel Intermediate Language", Z. Ariola et al,
   Fourth Intl Conf Func Prog Langs and Comp Arch, ACM Sept
   1989].