  plstyl(nels, mark, space)
  *************************

  plstyl

  This sets up the line style for all lines subsequently drawn. A line
  consists of segments in which the pen is alternately down and up. The
  lengths of these segments are passed in the arrays mark and space
  respectively. The number of mark-space pairs is specified by nels. In order
  to return the line style to the default continuous line, plstyl should be
  called with nels=0.(also see pllsty)

  nels (PLINT, input): The number of mark and space elements in a line.
  Thus a simple broken line can be obtained by setting nels=1. A continuous
  line is specified by setting nels=0.

  mark (PLINT *, input): Pointer to array with the lengths of the segments
  during which the pen is down, measured in micrometers.

  space (PLINT *, input): Pointer to array with the lengths of the
  segments during which the pen is up, measured in micrometers.

