> \boxXX=
\hbox(10.0+0.0)x100.0
.\vbox(10.0+0.0)x100.0
..\glue -30.0
..\glue 14.0
..\glue 0.0 plus -1.0
..\glue(\parskip) 0.0 plus 1.0
..\glue(\baselineskip) 6.0
..\hbox(3.0+2.0)x100.0, glue set 74.0fil
...\glue(\leftskip) 12.0
...\rule(3.0+2.0)x1.0
...\penalty 10000
...\glue(\parfillskip) 0.0 plus 1.0fil
...\glue(\rightskip) 13.0
..\glue 0.0 plus 1.0fil
..\glue 15.0