Introduce symbols as follows:

 O > symbol
 As2>  Here are the current symbols :
 As2>  .ID_R 51
 As2>  .ID_A N
 As2>  .ID_M BREF2
 As2> Symbol name : map
 As2> Symbol expansion (=delete symbol from list) : 2fofc.map
 As2> Symbol inserted.

Note that when you define the symbol, you must NOT include the dollar sign, only when you reference it. Also note that if you define symbols inside a macro, you should put the command and the two arguments on separate lines (this is due to a bug, I think), for example:

  ! mymacro.omac
  ...
  symbol
  map
  # Which map do you want to contour ? #
  print ... Using map file $map
  map_file $map
  ...