DEFINE /TRIM

        [SIC\]DEFINE IMAGE|HEADER Var1 File1 Key1 [Var2 File2 Key2 [...]]
                  /TRIM [Rank] [/GLOBAL]

    Attempt to trim trailing degenerate dimensions up to the specified Rank.
    If no Rank is given, trim all possible trailing degenerate dimensions.

    If Rank is positive, the defined header or image will have exactly  Rank
    dimensions.  An error occur if the corresponding file has non-degenerate
    dimensions beyond this rank.  If the file  is  of  lower  dimensionality
    than  the  specified Rank, its dimensionality is extended by  adding de-
    generate dimensions up to Rank.

    If Rank is negative, trim all possible trailing  degenerate  dimensions,
    and  return  an  error  if  the final dimensionality remains larger than
    Rank.

    Examples:
      Assume file.gdf contains a 3-D array of dimensions [Nx,Ny,1]
      DEFINE IMAG A file.gdf READ
        will return the 3-D array A[Nx,Ny,1]
      DEFINE IMAG A file.gdf READ /TRIM 4
        will return the 4-D array A[Nx,Ny,1,1]
      DEFINE IMAG A file.gdf READ /TRIM 1
        will produce an error (same with /TRIM -1)
      DEFINE IMAG A file.gdf READ /TRIM -4
        will return the 2-D array A[Nx,Ny]
      DEFINE IMAG A file.gdf READ /TRIM
        will also return the 2-D array A[Nx,Ny]