Constants (The GNU Awk User’s Guide)

From Get docs

6.1.1 Constant Expressions

The simplest type of expression is the constant, which always has the same value. There are three types of constants: numeric, string, and regular expression.

Each is used in the appropriate context when you need a data value that isn’t going to change. Numeric constants can have different forms, but are internally stored in an identical manner.

Scalar Constants    Numeric and string constants.
Nondecimal-numbers    What are octal and hex numbers.
Regexp Constants    Regular Expression constants.