Database Field Attributes - Listbox
Display
Caption
Enter a caption to describe this field. This will appear on the database window form.
Hint
Enter a hint that will be displayed when the cursor hovers over the entry field on the database window form.
Database Field
Field
From the drop-down list choose the required database field. This list will only contain those fields that are valid for the field type chosen above.
Field in layer table
This option is only visible if the particular database has the Table type PDB Layer Extra in the Database Table Structure. If this is the case the field drop-down list will contain appropriate field names from the LAYERS database table as well. Selecting one of those fields will cause this option to be automatically checked.
This option is required so that Impact can correctly store the data for fields in the LAYERS table. Also, so it can distinguish between a field with the same name being added to both the LAYERS and ONE_UP table, for example. When this option is checked the data is stored internally with the name LAYERS.L_FIELD rather than just L_FIELD as it would for ONE_UP columns.
Value cannot be modified (Read-only)
Switch this option on to make this field read-only.
Value is not required until drawing Save
Any non-nullable fields (see Can be empty in database entry windows on the Table Field form) can have this option set. This will allow you to close the database entry window even when nothing has been entered. However, you will not be allowed to save the project until something has been entered for this field.
Use this field when performing a Find
Switch this option on to allow this field to be used when searching the database from the Find Window form. See also the options on the External Tables form.
List
List choices
Here, you can enter a series of strings, separated by the vertical bar, |, that will make up the list of choices. Alternatively, press the edit button 
which will open the List Choices window, in which you can enter the required strings.
Value
From the drop-down list choose one of the following:-
- List value can be edited
- List value cannot be edited
- List value is stored as an integer
Use full width Listbox
Switch this option on to use a wider listbox.