In this step, you define the coding masks for the assignment of keys when you are creating appropriation requests. The system determines the coding mask to be used, based on the key of the coding mask and the first characters of the appropriation request key. When these keys agree, the system tries to adapt the entered key to the coding mask. If this does not work, the system issues an error message. Using this method enables you to guarantee that the keys of the appropriation requests all have a given structure.