The SAP R/3 System uses the logic of Boolean algebra to define validation and substitution statements. A Boolean logical statement is a logical proposition that can be either true or false but not both. Statements can be linked together using operators such as AND, OR, and NOR to create complex statements.

Boolean algebra uses truth tables to determine the truth value (TRUE or FALSE) of logical statements. A truth table assigns the value T (TRUE) or F (FALSE) to each statement in a complex logical statement. This information can then be used to determine whether the complex statement itself is true or false.

The following graphic uses a truth table for the AND (conjunction) operator to determine whether a value should be substituted.

In this example, if the transaction contains account 500000 and cost center 150, then the combined statement is true and the value is substituted. If the transaction does not contain both account 500000 and cost center 150, the combined statement is false and the value is not substituted.

In the FI-SL application component, you can use a Boolean statement in one process and then use the same statement in another process by linking the statement to another statement. To use a Boolean statement in an FI-SL process or in another statement, you create a rule.

A rule is a Boolean statement that you can use as a prerequisite, as a check, or in another rule. Rules allow you to refer to frequently used Boolean statements by using the rule name.

Rules are used in the following FI-SL components:

• Validation

• Substitution

• Ledger selection

• Report Writer

• Rollups

The validation and substitution software also contains a Rule Manager, which contains all rules created in the FI-SL application component. The Rule Manager also processes rules when they are called from a validation/substitution callup point.