> \cals@last@context=the letter b.
> \cals@last@rs@below=macro:
->{{200pt}{2pt}{2pt}{7pt}}.
> \boxXX=
\vbox(20.0+0.0)x300.0
.\vbox(0.0+0.0)x10.0
..\hbox(20.0+0.0)x10.0
...\glue 0.0
...\hbox(20.0+0.0)x10.0
....\rule(*+0.0)x10.0
...\glue 0.0
.\hbox(0.0+0.0)x200.0
..\glue 0.0
..\glue -1.0
..\rule(2.0+2.0)x202.0
..\glue -1.0
..\glue 0.0
.\hbox(20.0+0.0)x300.0
..\glue 0.0
..\hbox(20.0+0.0)x300.0
...\vbox(20.0+0.0)x100.0, glue set 10.0fil
....\rule(10.0+0.0)x100.0
....\glue 0.0 plus 1.0fil
...\vbox(20.0+0.0)x200.0
....\rule(20.0+0.0)x200.0
....\glue 0.0 plus 1.0fil
..\glue 0.0
.\penalty 10000