(1) A string_literal is formed by a sequence of graphic characters (possibly none) enclosed between two quotation marks used as string brackets.
Syntax
string_literal ::= "{string_element}*"
string_element ::= "" | non_quotation_mark_graphic_character
(2) A string_element is either a pair of quotation marks (""), or a single graphic_character other than a quotation mark.
Semantics
(3) The sequence of characters of a string_literal is formed from the sequence of string_elements between the bracketing quotation marks, in the given order, with a string_element that is "" becoming a single quotation mark in the sequence of characters, and any other string_element being reproduced in the sequence.
(4) A null string literal is a string_literal with no string_elements between the quotation marks.
NOTES:
An end of line cannot appear in a string_literal.
Examples
"Message of the day:"
"" -- a null string literal
" " "A" """" -- three string literals of length 1
"Characters such as $, %, and } are allowed in string literals"