L($W410
    GROUP 1. Run title and other preliminaries
TEXT(0D BOILING IN VESSEL+PRESS RELIEF:  W412
TITLE
  DISPLAY
  This case is similar to case 410, except that a pressure-relief
  valve is provided, to enable vapour to escape.
  ENDDIS
    GROUP 13. Boundary conditions and special sources
   ** Pressure relief...
PATCH(RELIEP,CELL,1,1,1,1,1,1,1,LSTEP)
COVAL(RELIEP,P1,FIXP,0.0)