Literals are expression values that are hard-coded into the message selector. In the message selector shown here, 30, 100.00, and 'Smith' are all literals:

Age < 30 AND Weight >= 100.00 AND LName = 'Smith'

String literals are enclosed in single quotes. An apostrophe or single quote can be included in a String literal by using two single quotes (e.g., 'Smith''s').

Numeric literals are expressed using exact numerical (+22, 30, -52134), approximate numerical with decimal (-33.22, 100.00, +7.0), or scientific (-9E4, 3.5E6) notation.

Boolean literals are expressed as TRUE or FALSE.