Tracing a Validation/Substitution/Rule 
Using the Extras
® Switch on trace function, you activate a tracing function that allows you to test a validation/substitution/rule during the posting process. While posting a document, the system calls the validation/substitution/rule and displays the rule contents, as well as how the data is used for validation or substitution. This function allows you to diagnose possible errors in the validation/substitution/rule definition.
You can only trace one validation at a time, but one substitution and one rule can also be active simultaneously; this is also true when you are tracing a substitution or rule. The tracing function is only activated for the user who has turned on the trace function.

You can use the trace function for one validation/substitution/rule, for all validations/substitutions/rules or not for any validations/substitutions/rules.
Procedure

If you want to use the trace function for all validations/substitutions/rules, choose Extras
® Switch on total trace.When the validation/substitution/rule is called, the system displays the result of the validation/substitution/rule that is used within the posting transaction.

If you use the single trace switch off, this switches off the trace function automatically for all the other validations/substitutions/rules.