.G1
label left "composition"
label bot "residue"
frame solid right invis top invis wid 5.0 ht 3.0
coord x 1, 21 y 0, 0.15
ticks bot off
copy "compo.dat" thru X
  line from $1,0 to $1,$3
  line from $1,$3 to $1+1,$3
  line from $1+1,$3 to $1+1,0
  "$2" at $1+0.5,-0.01
  line dotted from $1,$4 to $1+1,$4
X
.G2
