From Portable Document Format - Reference Manual - Version 1.2 (pag 44)
4.4 Strings
A string is a sequence of characters delimited by parentheses. If a string is
too long to be conveniently placed on a single line, it may be split across
multiple lines by using the backslash (\) character at the end of a line to
indicate that the string continues on the following line. When this occurs, the
backslash and end-of-line characters are not considered part of the string.
Examples of strings are:
( This is string number 1? )
( strangeonium spectroscopy )
(This string is split \
across \
three lines)
Within a string, the backslash character is used as an escape to specify
unbalanced parentheses, non-printing ASCII characters, and the backslash
character itself.
This escape mechanism is the same as for PostScript language strings, described
in Section 3.2.2 of the PostScript Language Reference Manual, Second Edition.
Table 4.1 lists the escape sequences for PDF.
Table 4.1 Escape sequences in strings
\n linefeed
\r carriage return
\t horizontal tab
\b backspace
\f formfeed
\\ backslash
\( left parenthesis
\) right parenthesis
\ ddd character code ddd (octal)
Use of the \ ddd escape sequence is the preferred way to represent characters
outside the printable ASCII character set, in order to minimize potential
problems transmitting or storing the characters. The number ddd may contain
one, two, or three octal digits. An example of a string with an octal character
in it is:
(string with \245two octal characters\307)
