Possible entries for selection screen field

Hi,

I have created a custom DDIC table Z_TAB which contains 3 fields of type char. The table contains about 100 rows of data. I want that at the selection screen, for each selection field a list of entries in the table should appear. E.g. Data rows:

Field1 Field2 Field3

aaaaa bbbbb ccccc

bbbbb bbbbb ccccc

ccccc bbbbb ccccc

(contd.) (contd.) (contd.)

Now at the selection screen:

Field1 _________

Field2 _________

Field3 _________

It is required that at selection screen:

Field1 should give the option of entries: aaaaa, bbbbb, ccccc, ...

Field2 should give the option of entries: bbbbb, ...

Field3 should give the option of entries: ccccc, ...

and so on, like for the standard DDIC tables.

How can this be achieved? Help is appreciated.

Regards