This is TeX, WAITS Version 0.6 (format=plain 82.11.4)  6 NOV 1982 08:46
**braces
(BRACES.TEX[TEX,DEK]
{vertical mode: \tracingonline}

{\tracingmacros}
{\hbox}

\lbrace ->{{\setcount 0=`}}
{restricted horizontal mode: begin-group character {}
{\setcount}
{end-group character }}
{the letter x}

\rbrace ->{\setcount 0=`{}}
{begin-group character {}
{\setcount}
{end-group character }}
{end-group character }}
{vertical mode: \showlists}

### vertical mode entered at line 0
### current page:
\glue(\topskip) 5.69446
\hbox(4.30554+0.0)x5.0
.\tenrm x
total height 10.0
 goal height 643.20255
prevdepth 0.0

! OK.
l.5 \showlists
              
? 
{\halign}

\lbrace ->{{\setcount 0=`}}
{restricted horizontal mode: the letter a}
{begin-group character {}
{begin-group character {}
{\setcount}
{end-group character }}
{the letter b}
{end of alignment template}
! Missing } inserted.
<to be read again> 
                   }
<to be read again> 
                   \ENDTEMPLATE.
l.7 \lbrace&
            \rbrace\cr
? 
{end-group character }}
{end of alignment template}

\rbrace ->{\setcount 0=`{}}
{the letter c}
{begin-group character {}
{\setcount}
{end-group character }}
{end-group character }}
! Missing \cr inserted.
<to be read again> 
                   \cr 
<to be read again> 
                   }
l.7 \lbrace&\rbrace
                   \cr
? h
I'm guessing that you meant to end an alignment here.

? 2
l.7 \lbrace&\rbrace
                   \cr
? 
{\cr}
! Missing } inserted.
<to be read again> 
                   \cr 
l.7 \lbrace&\rbrace\cr
                      
? 
{end-group character ['201]}
! Missing \cr inserted.
<to be read again> 
                   \cr 
<to be read again> 
                   }
<to be read again> 
                   \cr 
l.7 \lbrace&\rbrace\cr
                      
? 2
<to be read again> 
                   \cr 
l.7 \lbrace&\rbrace\cr
                      
? 
{\cr}
! Missing } inserted.
<to be read again> 
                   \cr 
l.7 \lbrace&\rbrace\cr
                      
? 
{end-group character ['201]}
! Missing \cr inserted.
<to be read again> 
                   \cr 
<to be read again> 
                   }
<to be read again> 
                   \cr 
l.7 \lbrace&\rbrace\cr
                      
? x
No output file.