\emph{However}, if you want to include a literal \dfn{backslash} in a
regular expression represented as a string literal, you have to
\emph{quadruple} it or enclose it in a singleton character class.
-E.g.\ to extract \LaTeX\ \samp{\e section\{{\rm
-\ldots}\}} headers from a document, you can use this pattern:
+E.g.\ to extract \LaTeX\ \samp{\e section\{\textrm{\ldots}\}} headers
+from a document, you can use this pattern:
\code{'[\e ]section\{\e (.*\e )\}'}. \emph{Another exception:}
the escape sequece \samp{\e b} is significant in string literals
(where it means the ASCII bell character) as well as in Emacs regular