ABAP Keyword Documentation → ABAP − Reference → Program Flow Logic → Expressions and Functions for Conditions → log_exp - Logical Expressions → rel_exp - Predicates
rel_exp - Predicate Functions
The return value of a predicate function is a truth value. A predicate function is a special formulation of a relational expression and, like any relational expression, can be a full logical expression or part of a logical expression. This means it can be specified as a condition in control statements and other statements, as an argument in Boolean functions or conditional expressions, or in joins with Boolean operators.
Other versions: 7.31 | 7.40 | 7.54
Note
The return value of a predicate function cannot be used in all operand positions for data objects. This is because Boolean data objects for the truth values true or false are unknown to ABAP.