\threecol{{\bf class of characters}}{{\bf match these}}{{\bf match others}}
\threecol{explicit set}{[ {\rm$\ldots$} ]}{[^ {\rm$\ldots$} ]}
\threecol{word-syntax character}{\\w}{\\W}
\threecol{character with syntax {\it c}}{\\s{\it c}}{\\S{\it c}}
\threecol{{\bf class of characters}}{{\bf match these}}{{\bf match others}}
\threecol{explicit set}{[ {\rm$\ldots$} ]}{[^ {\rm$\ldots$} ]}
\threecol{word-syntax character}{\\w}{\\W}
\threecol{character with syntax {\it c}}{\\s{\it c}}{\\S{\it c}}