anchor.diff:  C     clip:  
   C----
         call gcmdln(x1,x2,nx,dx,y1,y2,ny,dy,z,ofile,p,ref,xsec,xz,clip,
  -     1            datain)
  +     1            datain,expflg)
         if (datain.eq.1) goto 9001
   C Check that limits and increments are properly defined
         if (x2.lt.x1) call usage('!! Error: X2 must be greater than X1')
  
positive.code:       xz = 0
        clip = 'none'
        datain = 0
        do 100 i = 1,5
            ref(i) = -1.0d0
    100 continue
  
negative.code:       CHARACTER*200 clip,line
        REAL*8 x1,x2,y1,y2,dx,dy,dz,dd,ref(5),dist,az,lo,la
        REAL*8 x,y,z,xx(1000),yy(1000),zsave
        INTEGER i,j,k,nx,ny,p,xsec,xz,nn,io,datain,expflg
  
  C----
  C Get parameters from the command line
  