Control Mechanisms (Double Verification Principle, Test Procedures, etc.) 
Control Mechanisms (Double Verification Principle, Test Procedures, etc.)
The following are additional methods you can use to protect especially critical data when you create or change data.
Note that you can combine the symmetrical and asymmetrical double verification principles as long as they are used for different infotypes (or different subtypes of an infotype). It is not advisable to combine the asymmetrical and symmetrical double verification principles for the same infotype/subtype because the system response is undefined for this type of combination.
The test procedures and the change document are, in comparison, independent mechanisms. You can, therefore, use any combination of these mechanisms and in conjunction with the double verification principle.