\hd{Inline verbatim}
+\inlineverbon
Lo and behold: |a quick brown fox| {\showspacestrue |jumps over the lazy dog|} |!@#$%^&*()\_|
+\inlineverboff
+When turned off, vertical lines work as usually: $|a-b| \ge 0$.
+
\hd{Block verbatim}
\noindent Pre-verbatim
\gdef\showsp@ces{\ifshowspaces\let =\sp@ce\fi}
\global\let =\ }
-\catcode124=\active % Make | active
-\def\ttst@rt{\begingroup\setverb@tim\let|=\endgroup}
-\let|=\ttst@rt
+{\catcode124=\active % Make | active
+\gdef\ttst@rt{\begingroup\setverb@tim\let|=\endgroup}
+\gdef\inlineverbon{\catcode124=\active\let|=\ttst@rt}
+\gdef\inlineverboff{\catcode124=12}
+}
% Typesetting of verbatim blocks:
% - the block is enclosed in balanced {}'s