DCL:GRPH2:UDPACK: Contour Routines: Explanation of Subroutines
Sets the value of the contour level used by UDCNTR (or UDCNTZ) with an array giving the grid-point values and the step size or the approximate number of levels.
CALL UDGCLB(Z,MX,NX,NY,DX)
Z, MX, NX, NY See UDCNTR (Section 8.2.1). DX See UDGCLA (Section 8.2.3)