\begin

// [from the LaTeX command] With \end, used humorously in writing to indicate a context or to remark on the surrounded text. For example:

     \begin{flame}
     Predicate logic is the only good programming
     language.  Anyone who would use anything else
     is an idiot.  Also, all computers should be
     tredecimal instead of binary.
     \end{flame}

The Scribe users at CMU and elsewhere used to use @Begin/@End in an identical way (LaTeX was built to resemble Scribe). On USENET, this construct would more frequently be rendered as `<FLAME ON>' and `<FLAME OFF>', or `#ifdef FLAME' and `#endif FLAME''.