anchor.diff:        xsec = 0
         xz = 0
         clip = 'none'
  +      datain = 0
         do 100 i = 1,5
             ref(i) = -1.0d0
     100 continue
  
positive.code: C     xz:    
  C     clip:  
  C----
        call gcmdln(x1,x2,nx,dx,y1,y2,ny,dy,z,ofile,p,ref,xsec,xz,clip)
  C Check that limits and increments are properly defined
        if (x2.lt.x1) call usage('!! Error: X2 must be greater than X1')
        if (y2.lt.y1) call usage('!! Error: Y2 must be greater than Y1')
  
negative.code:       endif
        if (ref(5).gt.8.5d1) then
            call usage('!! Error: fault dip greater than 85')
        endif
   9001 if (datain.eq.1.and.clip.eq.'none') then
            call usage('!! Error: can only check if input is inside '//
       1               'polygon along with -clip')
        endif
  C If output file unspecified, print result to standard output
        if (ofile.eq.'none'.and.p.eq.0) p = 1
  