58: How do I use regexps (regular expressions) in Emacs? See "Regexps" in the on-line manual. WARNING: The "or" operator is `\|', not `|', and the grouping operators are `\(' and `\)'. Also, the string syntax for a backslash is `\\'. To specify a regular expression like xxx\(foo\|bar\) in a Lisp string, use "xxx\\(foo\\|bar\\)" Notice the doubled backslashes! WARNING: Unlike in Unix grep, sed, etc., a complement character set ([^...]) can match a newline character (LFD aka C-j aka \n), unless newline is mentioned as one of the characters not to match. WARNING: The character syntax regexps (e.g., "\sw") are not meaningful inside character set regexps (e.g., "[aeiou]"). (This is actually typical for regexp syntax.)