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Predefined Functions
ABAP provides a set of predefined functions. A predefined function returns a return value for one or more arguments. Predefined functions can be called by functions in certain operand positions.
Predefined functions can be called functionally at certain operand positions. When a predefined function is called at an operand position, the function is executed before the operand is used and the return value of the predefined function is used as the operand, in accordance with its data type.
A predefined function is covered by a functional method, regardless of how many arguments it has.

Predefined Functions - Syntax

Predefined Functions - Overview