doc-src/Ref/defining.tex

 longid    & =   & id\mbox{\tt .}id~\dots~id \\
 var       & =   & \mbox{\tt ?}id ~~|~~ \mbox{\tt ?}id\mbox{\tt .}nat \\
 tid       & =   & \mbox{\tt '}id \\
 tvar      & =   & \mbox{\tt ?}tid ~~|~~
                   \mbox{\tt ?}tid\mbox{\tt .}nat \\
-xnum      & =   & \mbox{\tt \#}nat ~~|~~ \mbox{\tt \#\char`\~}nat \\
+xnum      & =   & \mbox{\tt \#}nat ~~|~~ \mbox{\tt \#-}nat \\
 xstr      & =   & \mbox{\tt ''\rm text\tt ''} \\[1ex]
 letter    & =   & \mbox{one of {\tt a}\dots {\tt z} {\tt A}\dots {\tt Z}} \\
 digit     & =   & \mbox{one of {\tt 0}\dots {\tt 9}} \\
 quasiletter & =  & letter ~~|~~ digit ~~|~~ \mbox{\tt _} ~~|~~ \mbox{\tt '} \\
 nat       & =   & digit^+