SET FREQUENCY

          [ASTRO\]SET FREQUENCY [MainAxis SecondAxis]

    Define  the  main  and secondary frequency frames of the current session
    for EMIR and NOEMA receiver and backend frequency coverages.  The  lower
    axis of the plots is always in the main frequency frame, while the upper
    axis displays the secondary frame.  Possible frames are:
      REST,LSR,RF for the main frame and
      REST,LSR,RF,IF1,IF2,IMREST,IMLSR,IMRF,CHUNK,NULL (i.e. nothing  drawn)
    for  the  secondary  frame.  When CHUNK is chosen, the chunk numbers are
    indicated in the upper axis.

    SET FREQUENCY DEFAULTS comes back to the  default  (main='REST',  second
    axis='NULL').   Note  that the main frequency frame defines not only the
    lower axis of the plot but also the frame in which input and output fre-
    quencies are given.

    With no arguments, SET FREQUENCY displays the current content of the ax-
    is.