A backslash occurring inside integers in 0' notation or inside
quoted atoms or strings has special meaning, and indicates the
start of an escape sequence.  Character escaping can be turned off
for compatibility with old code.  The following escape sequences
exist:
     
\b
     \t
     \n
     \v
     \f
     \r
     \e
     \d
     \^?   SICStus only
     \a
     \xhex-digit...\   ISO only
     \xhex-digithex-digit   SICStus only
     \octal-digit...\  ISO only
     \octal-digit?octal-digit?octal-digit  SICStus only
     \^char  SICStus only
     char mod 32, where char is a
letter.
     \<LFD>
     \layout-char  SICstus only
     \c  SICStus only
     \\, \', \", \`
     \.
     \other  SICStus only