Backslash substitution is performed whenever the interpreter comes
across a backslash. The backslash is an escape character and when it is
encountered is causes the interpreter to handle the next characters
specially. Commonly escaped characters are \a for audible bell,
\b for backspace, \f for form feed, \n for newline,
\r for carriage return, \t for horizontal tab, and
\v for vertical tab. Double-backslash, \\, is substituted
with a single backslash. Other special backslash substitutions have the
following forms:
\ooo
ooo give the octal value of the escaped character
\xHH
x denotes that the following hexadecimal digits are the value
of the escaped character
Any other character that is backslash escaped is simply substituted by
the character itself. For example, \W is replaced by W.