MACRO dbug key=help
  if ([key] = help) then
    message 'Usage: dbug [-]<keyword1> [ [-]<keyword2> [...]]'
    message 'where <keyword> is one of the following:'
    message '1) none - disables all debugging options'
    message '2) printout - enables step-by-step debug printout during tracking'
    message '3) store - stores step-by-step track coordinates during tracking'
    message '4) plot - plots the tracks on the current drawing view'
    message '5) plotnow - plots at every step instead of at end of track'
    message '6) neutrals - renders neutral tracks visible during plotting'
    exitm
  endif
  while [1] <> ' ' do
    case [1] in
    (none)
        switch 1 0
        switch 2 0
        switch 3 0
        debug off
    (-none)
        message 'This is meaningless!'
    (printout)
        switch 2 2
        debug on
    (-printout)
        switch 2 0
    (store)
        switch 3 1
        debug on
    (-store)
        switch 3 0
    (plot)
        switch 3 1
        switch 2 3
        debug on
    (-plot)
        switch 2 0
    (plotnow)
        switch 2 4
        debug on
    (-plotnow)
        switch 2 0
    (neutrals)
        switch 4 0
        debug on
    (-neutrals)
        switch 4 3
        switch 2 3
    endcase
    shift
  endwhile
RETURN