Combo Box Control (Forms) [Access 2003 VBA Language Reference]
The combo box control combines the features of a text box and a list box. Use a combo box when you want the option of either typing a value or selecting a value from a predefined list.
Note This control should not be confused with the Dynamic HTML drop-down list box control used on a data access page. For information about a drop-down list box control on a data access page, see Drop-down List Box Control (Data Access Page).
In Form view, Microsoft Access doesn't display the list until you click the combo box's arrow.
If you have Control Wizards on before you select the combo box tool, you can create a combo box with a wizard. To turn Control Wizards on or off, click the Control Wizards button in the toolbox.
The setting of the LimitToList property determines whether you can enter values that aren't in the list.
The list can be single- or multiple-column, and the columns can appear with or without headings.