When you create single screens and list screens using the ABAP Screen Painter, you determine the attributes of individual screens. However, the same screen is always used for various functions such as to create, display, maintain, and delete infotype records. For this reason, you cannot specify whether entries can be made in a screen field when maintaining the screen. It is also possible that particular screen fields must be hidden, depending on the employee’s organizational data.

In other words, some attributes are not specified to be generally applicable; instead, they are specified during runtime. The appearance of the screens changes depending on the function chosen by the user or the data being processed.

• The same single screens are used for the Display master data and Maintain master data functions. However, it must only be possible to make entries in the fields if the Maintain master data function is chosen. For this reason, you must determine whether entries can be made in the fields or not depending on the function to be carried out.
• The screens used to enter company car data in the Internal Control infotype (0032) must be hidden for employees assigned to the employee group for pensioners.

Screen control functions have already been implemented in the main infotype program. These functions read the values from the modification groups for individual screen fields and set their attributes in accordance with the values. The meaning of the values for modification groups is determined in tables.

When you develop infotypes, you can effect screen control as follows:

• You can determine whether entries can be made in fields, or you can choose to hide screen fields, depending on the function to be carried out.

• You can use alternative screens, or determine whether entries can be made in fields, or hide screen fields using control data in table T588M.

If you use both of the above to effect screen control for a screen field, screen control using table T588M has higher priority.

Modification group 2 is used internally.

Modification group 4 is not used in the standard system because it is reserved for customers. If you use this field, you are modifying the SAP standard system.