This is TeX, WAITS Version 0.9 (format=plain 82.12.2)  5 DEC 1982 15:25
**\tracingall

*\setbox1=\vbox to 1pt{\vss\hbox to 1pt{\hss\lower1pt\null}}
{\setbox}
{internal vertical mode: \vss}
{\hbox}
{restricted horizontal mode: \hss}
{\lower}

\null ->\hbox {}
{end-group character }}
{end-group character }}
{internal vertical mode: end-group character }}
{vertical mode: blank space}

*\setbox2=\vbox to 2pt{\vss\hbox to 2pt{\hss\lower2pt\null}}
{\setbox}
{internal vertical mode: \vss}
{\hbox}
{restricted horizontal mode: \hss}
{\lower}

\null ->\hbox {}
{end-group character }}
{end-group character }}
{internal vertical mode: end-group character }}
{vertical mode: blank space}

*\showbox1
{\showbox}
> \box1=
\vbox(1.0+1.0)x1.0, glue set 1.0fil
.\glue 0.0 plus 1.0fil minus 1.0fil
.\hbox(0.0+1.0)x1.0, glue set 1.0fil
..\glue 0.0 plus 1.0fil minus 1.0fil
..\hbox(0.0+0.0)x0.0, shifted 1.0

! OK.
<*> \showbox1
             
? 

*\showbox2
{\showbox}
> \box2=
\vbox(2.0+2.0)x2.0, glue set 2.0fil
.\glue 0.0 plus 1.0fil minus 1.0fil
.\hbox(0.0+2.0)x2.0, glue set 2.0fil
..\glue 0.0 plus 1.0fil minus 1.0fil
..\hbox(0.0+0.0)x0.0, shifted 2.0

! OK.
<*> \showbox2
             
? 

*\setbox3=\vbox to 3pt{\moveright3pt\copy1\vskip-3ptplus3fil\copy2}
{\setbox}
{internal vertical mode: \moveright}
{\vskip}
{\copy}
{end-group character }}

Overfull \vbox (7.0pt too high) detected at line 0

\vbox(3.0+2.0)x4.0
.\vbox(1.0+1.0)x1.0, glue set 1.0fil, shifted 3.0
..\glue 0.0 plus 1.0fil minus 1.0fil
..\hbox(0.0+1.0)x1.0, glue set 1.0fil
...\glue 0.0 plus 1.0fil minus 1.0fil
...\hbox(0.0+0.0)x0.0, shifted 1.0
.\glue -3.0 plus -3.0fil
.\glue(\baselineskip) 9.0
.\vbox(2.0+2.0)x2.0, glue set 2.0fil
..\glue 0.0 plus 1.0fil minus 1.0fil
..\hbox(0.0+2.0)x2.0, glue set 2.0fil
...\glue 0.0 plus 1.0fil minus 1.0fil
...\hbox(0.0+0.0)x0.0, shifted 2.0

{vertical mode: blank space}

*\baselineskip0pt\lineskip0pt\lineskiplimit0pt\setbox3=\vbox to 3pt{\moveright3p
t\copy1\vskip-3ptplus3fil\copy2}
{\baselineskip}
{\lineskip}
{\lineskiplimit}
{\setbox}
{internal vertical mode: \moveright}
{\vskip}
{\copy}
{end-group character }}
{vertical mode: blank space}

*\showbox3
{\showbox}
> \box3=
\vbox(3.0+2.0)x4.0, glue set -0.66667fil
.\vbox(1.0+1.0)x1.0, glue set 1.0fil, shifted 3.0
..\glue 0.0 plus 1.0fil minus 1.0fil
..\hbox(0.0+1.0)x1.0, glue set 1.0fil
...\glue 0.0 plus 1.0fil minus 1.0fil
...\hbox(0.0+0.0)x0.0, shifted 1.0
.\glue -3.0 plus -3.0fil
.\glue(\lineskip) 0.0
.\vbox(2.0+2.0)x2.0, glue set 2.0fil
..\glue 0.0 plus 1.0fil minus 1.0fil
..\hbox(0.0+2.0)x2.0, glue set 2.0fil
...\glue 0.0 plus 1.0fil minus 1.0fil
...\hbox(0.0+0.0)x0.0, shifted 2.0

! OK.
<*> \showbox3
             
? 

*\baselineskip=9pt minus 3fil
{\baselineskip}

*\def\doit{\setbox4=\vbox to 4pt{\vss\copy1\moveleft4pt\copy2\vss}\showbox4 }
{\def}

*\doit

\doit ->\setbox 4=\vbox to 4pt{\vss \copy 1\moveleft 4pt\copy 2\vss }\showbox 4 
{\setbox}
{internal vertical mode: \vss}
{\copy}
{\moveleft}
{\vss}
{end-group character }}
{vertical mode: \showbox}
> \box4=
\vbox(4.0+0.0)x1.0, glue set - 1.60001fil
.\glue 0.0 plus 1.0fil minus 1.0fil
.\vbox(1.0+1.0)x1.0, glue set 1.0fil
..\glue 0.0 plus 1.0fil minus 1.0fil
..\hbox(0.0+1.0)x1.0, glue set 1.0fil
...\glue 0.0 plus 1.0fil minus 1.0fil
...\hbox(0.0+0.0)x0.0, shifted 1.0
.\glue(\baselineskip) 6.0 minus 3.0fil
.\vbox(2.0+2.0)x2.0, glue set 2.0fil, shifted -4.0
..\glue 0.0 plus 1.0fil minus 1.0fil
..\hbox(0.0+2.0)x2.0, glue set 2.0fil
...\glue 0.0 plus 1.0fil minus 1.0fil
...\hbox(0.0+0.0)x0.0, shifted 2.0
.\glue 0.0 plus 1.0fil minus 1.0fil

! OK.
\doit ...py 1\moveleft 4pt\copy 2\vss }\showbox 4 
                                                  
<*> \doit
         
? 

*\boxmaxdepth-4pt
{\boxmaxdepth}

*\doit

\doit ->\setbox 4=\vbox to 4pt{\vss \copy 1\moveleft 4pt\copy 2\vss }\showbox 4 
{\setbox}
{internal vertical mode: \vss}
{\copy}
{\moveleft}
{\vss}
{end-group character }}
{vertical mode: \showbox}
> \box4=
\vbox(4.0+-4.0)x1.0, glue set - 2.39999fil
.\glue 0.0 plus 1.0fil minus 1.0fil
.\vbox(1.0+1.0)x1.0, glue set 1.0fil
..\glue 0.0 plus 1.0fil minus 1.0fil
..\hbox(0.0+1.0)x1.0, glue set 1.0fil
...\glue 0.0 plus 1.0fil minus 1.0fil
...\hbox(0.0+0.0)x0.0, shifted 1.0
.\glue(\baselineskip) 6.0 minus 3.0fil
.\vbox(2.0+2.0)x2.0, glue set 2.0fil, shifted -4.0
..\glue 0.0 plus 1.0fil minus 1.0fil
..\hbox(0.0+2.0)x2.0, glue set 2.0fil
...\glue 0.0 plus 1.0fil minus 1.0fil
...\hbox(0.0+0.0)x0.0, shifted 2.0
.\glue 0.0 plus 1.0fil minus 1.0fil

! OK.
\doit ...py 1\moveleft 4pt\copy 2\vss }\showbox 4 
                                                  
<*> \doit
         
? x
Statistics for this run:
1526 strings of total length 24755
...TeX capacity is currently 3000 31000
Maximum memory usage 325&2285
...TeX capacity is currently 25000&36001
666 multiletter control sequences
...TeX capacity is currently 2100
19673 words of font info for 76 fonts
...TeX capacity is currently 25000 100
13 hyphenation exceptions
...TeX capacity is currently 307
Maximum stack usage 1i,2n,0p,112b,17s
...TeX capacity is currently 80i,40n,30p,500b,300s
No output file.