Level 2 Help for MAPGRID

   input image file name

   Output image file name.  The output picture consists of the
   input with the appropriate grid patern superimposed.

   (SL,SS,NL,NS)  SL and SS are, respectively the starting data
   record and starting byte in the input picture at which processing
   is to begin.  NL and NS are, respectively, the number of data
   record and the number of bytes to be processed from the input
   data set.  When the size field is defaulted, values for SL and
   SS of 1 will be assumed, and values for NL and NS will be assigned
   equal to the values in the input data set system label.  In this
   way,the output data will be equal in size to the input data.

   This keyword causes a 0 DN and 255 DN grid pattern to be used.

   This keyword causes a modulated grid patern to be used with the
   specicied integer value.  The integer represents the constant for
   modulation.  If neither BLAC nor MODU is specified, the modulated
   grid patern is used with the integer value defaulted to 64.