1 MSUBTRACT
  Syntax: MSUBTRACT ido&idbo id1[&idb1] id2[:id2n][&idb2[:idbn2]] ...
   where: ido              is the output histogram identifier
          idbo             is the (optional) output secondary identifier
          id1              is the histogram identifier from which the others
                           are subtracted
          idb1             is the (optional) input secondary identifier
          id2,...          are the histogram identifiers subtracted from id1
          idb2,...         are the (optional) secondary identifiers
          id2n,...         are the upper limits of an (optional) range
          idb2n,...        are the upper limits of an (optional) range

  Subtracts a series of histograms (id2,...) from id1 to make a new one. To
  specify the secondary identifier, precede it by a `&', otherwise the default
  will be used.  (Use the `SET IDB' command to change the default).

  To subtract a range of histograms, you can specify a range of primary and/or
  secondary identifiers. For example, `MSUBTRACT 500&1 200&1 300:400&1' will
  subtract all histograms with primary identifiers 300 to 400 and secondary
  identifiers 1 from 200&1 and create histogram 500&1. If you give primary
  identifier 0, the operation will be performed on all plots with the given
  secondary identifier.

