
\newenvironment{exbox}%
   {\par\medskip\global\setbox2=\hbox\bgroup
    \newcommand{\exline}[3]% 
       {{\tt ##1} & $\rightarrow$ & {\tt '##2' ~/* {\rm\it ##3\/} */}\\}%
    \qquad\begin{tabular}{lll}}%
   {\end{tabular}\egroup\noindent
                        \framebox[\textwidth][l]{\unhbox2\hfill}\par\medskip}


\newcommand{\syntaxerror}[1]{number #1 (%
   \ifcase#1\or\or\or
      ``Program interrupted''\or
      ``Machine resources exhausted''\or
      ``Unmatched ``{\tt /*}'' or quote''\or
      ``{\tt WHEN} or {\tt OTHERWISE} expected''\or
      ``Unexpected {\tt THEN} or {\tt ELSE}''\or
      ``Unexpected WHEN or OTHERWISE''\or
      ``Unexpected or unmatched END''\or
      ``Control stack full''\or
      ``Clause > 500 characters''\or
      ``Invalid character in data''\or
      ``Incomplete {\tt DO}/{\tt SELECT}/{\tt IF}''\or
      ``Invalid hexadecimal or binary constant''\or
      ``Label not found''\or
      ``Unexpected {\tt PROCEDURE}''\or
      ``{\tt THEN} expected''\or
      ``String or symbol expected''\or
      ``Symbol expected''\or
      ``Invalid data on end of clause''\or\or
      ``Invalid data string''\or
      ``Invalid {\tt TRACE} request''\or
      ``Invalid sub-keyword found''\or
      ``Invalid whole number''\or
      ``Invalid {\tt DO} syntax''\or
      ``Invalid {\tt LEAVE} or {\tt ITERATE}''\or
      ``Environment name to long''\or
      ``Name or string too long''\or
      ``Name starts with number or \".\"''\or
      ``Invalid use of stem''\or
      ``Invalid expression result''\or
      ``Logical value not 0 or 1''\or
      ``Invalid expression''\or
      ``Unmatched ``('' in expression''\or
      ``Unexpected ``,'' or ``)''\,''\or
      ``Invalid template or pattern''\or
      ``Evaluation stack overflow''\or
      ``Incorrect call to routine''\or
      ``Bad aritmetric conversion''\or
      ``Arithmetic overflow/underflow''\or
      ``Routine not found''\or
      ``Function did not return data''\or
      ``No data specified on function''\or
      ``Invalid variable reference''\or\or
      ``Failure in system service''\or
      ``Interpreter failure''\fi}


