o<queuebuster> sub
  #<xmax>         = #1 (=9)
  #<ymax>         = #2 (=3)
  #<feed>         = #3 (=100)
  #<ct>           = #4 (=100)
  #<use_m6>       = #5 (=0)
  #<use_m66>      = #6 (=0)
  #<use_m38>      = #7 (=0)
  #<pauseatend>   = #8 (=1)

  g20 g61 g90 ;inches, exactpath,absolute
  g0 x0y0z0
  f#<feed>
  o<loop> repeat [#<ct>]
    m111
    g1 x#<xmax> y0

    o<um6> if [#<use_m6> GT 0]
      (debug, m6 queuebuster follows)
      t1m6      ;QB toolchange
    o<um6> endif

    o<um66> if [#<use_m66> GT 0]
      (debug, m66 queuebuster follows)
      m66p0l0   ;QB wait on input l0=immediate
    o<um66> endif

    o<um38> if [#<use_m38> GT 0]
      (debug, g38.3 queuebuster follows)
      g38.3z-.2 ; QB probe 
      g1 z0
    o<um38> endif

    g1          y#<ymax>
    g1 x0
    g1 x0       y0
    o<pas> if [#<pauseatend> GT 0]
      (debug, Paused, s to continue)
      m0
    o<pas> endif
  o<loop> endrepeat
o<queuebuster> endsub

; bad:  t0m6 g38.3 
; ok:   m66