In order to provide your own customized assistance for asset master data maintenance, the system enables you to define your own validation and substitution rules. You make these specifications in FI-AA Customizing (Define validation/Define substitution).

You create your own validation conditions, which serve as check rules when you create an asset master record. These customized check rules supplement the standard check rules. A validation condition consists of the following:

• Company code

• Specification of the point in time for the check

• Validation rule

A validation rule consists essentially of the following elements:

• Condition, under which the rule should be checked (such as, if the asset class is LVA)

• Check rule, that cannot be broken (such as depreciation key is GWG1 or GWG2)

• Number of the error message that the system should produce if the check rule is violated

You must define check rules and conditions which conform to Boolean logic.

The system checks the validation conditions when you change to a new screen while creating an asset master record. If a check rule is violated, the system displays an error message. You specify the number of this error message in the validation rule. You have to create this error message yourself (transaction SE61).

The following graphic shows the Customizing settings for a validation rule, and the actions of the user. The validation rule defined is "In asset class 1000 in depreciation area 01, only depreciation keys for buildings are allowed."

You can use substitution functions within the realm of asset master data maintenance for the following activities:

Substitution conditions enable you to create default values, in addition to the defaults from the asset class. Substitution conditions are based on freely definable rules, and are dependent on different master data fields in the asset master record.

The substitution conditions have the same structure as validation conditions. The most important part of the substitution is the substitution rule. A substitution rule consists primarily of the following:

• The conditions under which the rule should be checked

• Substitution if the requirements are met (setting of a constant value in a particular master record field). Or you can use a substitution exit with program code that determines the value to be entered in the master record field.

You define the substitution rules in FI-AA Customizing. They are based on Boolean logic, as the validation rules are.

You can still change values that have been proposed on the basis of substitution rules. You can change these values manually in the master data transaction. Values that you change manually are not changed again by the substitution rule.