Selection Texts
You can replace the standard texts that appear for parameters and selection criteria on the selection screen (see
Working with Selection Screens) with text elements.To change the text on the selection screen, select Selection texts from the ABAP Text Elements screen and choose Change.
On the following screen, the column Name already contains the names of the parameters and selection criteria of your program (see example below). Now you can enter a selection text of up to 30 characters for each parameter and selection criterion.
If you have created selection criteria for ABAP Dictionary fields, you can choose Utilities
® Copy DD texts. The system fills these selection texts automatically with the short texts assigned as attributes to the ABAP Dictionary fields. The entry DDIC occurs in the column Type of each line with Dictionary texts. You can mark single lines and choose Utilities ® Copy DD text. Then, the system treats only the marked lines. The text elements with dictionary texts appear in display mode. You can change them after marking the respective lines and choosing Utilities ® No DD text. The text element remains the same, but can now be modified. 
If a short text is changed in the ABAP Dictionary after it was copied as a selection text to the text pool, this change is not transferred automatically to the text pool. To adjust the dictionary texts in the text pool with the texts in the ABAP Dictionary, you must choose Utilities ® Supplement DD texts.
Save your changes by choosing Save.
If you change or delete any parameters or selection criteria in your program after you have maintained the selection texts once and then call selection text maintenance, you see a flagged checkbox in last column on the right (not used) for each text no longer required in the program. This facilitates the deletion of any unused selection texts. If you attempt to delete a selection text used in the program, the system outputs a warning message. When you store the selection texts, the system once again notes the existence of any unused texts and offers them to you for deletion.

Assume a program as follows:
PROGRAM SAPMZTST.
TABLES SBOOK.
PARAMETERS: TEXT(10).
SELECT-OPTIONS: SEL1 FOR SBOOK-CARRID,
SEL2 FOR SBOOK-CONNID.
The screen for changing the selection texts looks as follows:

When you choose Utilities
® Copy DD texts, it changes to:
Now, you can mark the line with (for example) SEL1 in column name and choose Utilities ® No DD text to change its selection text:

The selection text for parameter TEXT is also changed.
After saving the selection texts and starting SAPMZTST, the selection screen looks as follows:

Now, replace the parameter TEXT in the program by the parameter PARA:
PROGRAM SAPMZTST.
TABLES SBOOK.
PARAMETERS: PARA(10).
SELECT-OPTIONS: SEL1 FOR SBOOK-CARRID,
SEL2 FOR SBOOK-CONNID.
Then, if you call selection text maintenance again, the screen looks as follows after you have generated the program:

The new parameter PARA is displayed and the old parameter TEXT is flagged as Not used. If you save the selection text now, the system displays a dialog window that offers to delete all unused elements.