Escape Sequences \a Beep
\c "Control" caracter. \cD = CTRL-D
\f Form feed
\l Make the next letter lowercase
\n New line, return.
\r Carriage return.
\u Make the next letter uppercase
\x Enables hex numbers
\v Vertical tab
\\ Print backslash
\" Print double quotes
\ Escape next character if known otherwise print. Also allows octal numbers.
\L Make all letters lowercase until the \E
\U Make all letters uppercase until the \E
\Q Add a backslash-quote to all the nonalphanumerics until the \E
\E Terminates the effects of \L, \U, or \Q
\007 Any octal ASCII value
\x7f Any hexadecimal value
These look to be string pattern match escape sequences
\B - Matches everywhere except between a word character and non-word character
\A - Matches only at the beginning of a string
I have not