TICKSPACE

        [GREG1\]TICKSPACE SmallX BigX SmallY BigY

    Sets tick intervals (in User coordinates) for BOX or  default  intervals
    for  AXIS. SmallX refers to the interval between small tick marks on the
    X axis, BigX refers to the interval between large ticks, etc...  If  Big
    is  0,  the  axis routine will supply its own Big intervals according to
    the label limits and use your Small value if non zero.  To restore fully
    automatic  ticking,  set  Small  and  Big equal to 0.  To suppress small
    ticks, specify equal values for Small and Big.

    The Small and Big values are meaningless  for  LOGarithmic  axes,  which
    uses their own conventions. These conventions are not quite perfect, and
    if less than one decade is plotted, odds are good that you will not  get
    any labelling !...

    When using the /ABSOLUTE or /UNIT option for axis-drawing commands,  one
    has to keep in mind that Small and Big (if not 0) should be expressed:
      - in seconds of arc for declination or galactic (sexagesimal notation)
        axis, /ABSOLUTE option (one can usually multiply by 3600 the desired
        tick spacing)
      - in seconds of  time  for  right  ascension  axis,  /ABSOLUTE  option
        (multiply by 12)
      - in seconds, minutes or degrees when option /UNIT [SECOND, MINUTE  or
        DEGREE] is used.
    Thus in the case of a  user-defined  tick  spacing,  TICKSPACE  must  be
    redefined before using another option.