What is the functional module for drop down box ?

As well as input help, which appears in separate dialog boxes, you can also define input/output fields as dropdown boxes. A dropdown box offers the user a predefined set of input values from which to choose. It is not possible to type a entry into a dropdown box, instead, the user must use one of the values from the list. When the user chooses a value, the PAI event can be triggered simultaneously. If you use a dropdown box for a field, you cannot at the same time use the input help button.

List boxes are currently the only type of dropdown box supported. A list box is a value list containing a single text column of up to 80 characters. Internally, each text field has a key of up to 40 characters. When the user chooses a line, the contents of the text field are placed in the input field on the screen, and the contents of the key are placed in the screen field. The contents and length of the input/output field and the screen field are not necessarily the same.

To make an input/output field into a list box, you must set the value L or LISTBOX in the Dropdown attribute in the Screen Painter. The visLg attribute determines the output width of the list box and the field. You can assign a function code to a list box field. In this case, the PAI event is triggered as soon as the user chooses a value from the list, and the function code is placed in the SY-UCOMM and OK_CODE fields. If you do not assign a function code, the PAI event must be triggered in the usual way – that is, when the user chooses a pushbutton or an element from the GUI status.

If you have assigned a list box to an input/output field, you can use the Value list attribute of the screen element to determine how the value list should be compiled. There are two options:

· Value list from input help (recommended)

If you do not enter anything in the value list attribute, the text field uses the first column displayed in the input help assigned to the screen field. The input help can be defined in the ABAP Dictionary, the screen, or a POV dialog module. It should be laid out in two columns. The key is automatically filled.

· Value list from PBO modules (not recommended).

If you enter A in the value list attribute, you must fill the value list yourself before the screen is sent (for example, in the PBO event) using the function module VRM_SET_VALUES. When you do this, you must pass an internal table with the type VRM_VALUES to the import parameter VALUES of the function module. VRM_VALUES belongs to the type group VRM. The line type is a structure consisting of the two text fields KEY (length 40) and TEXT (length 80). In the table, you can combine possible user entries from the KEY field with any texts from the TEXT component. You specify the corresponding input/output field in the import parameter ID.