Quoting

Each metacharacter described in Syntax terminates a word unless the metacharacter is quoted. Characters can be quoted by enclosing them in a pair of single quotation marks (') or double quotation marks (").. Quoting characters forces MDB to interpret each character as itself without any special significance. A single quotation mark cannot appear inside single quotation marks. Inside double quotation marks, MDB recognizes the C programming language character escape sequences.