You can create lookups for your custom database tables and forms that you created in the User Database (UD) module.
Lookups are the windows that display when you press F4 from a field. These windows show valid data relating to the field.
Typically, lookups are assigned only to fields that require valid input from a specific database table, such as Vendor (APVM), Job (JCJM), Phase (JCPM), and so forth. Once you create a lookup, you can use the Field Properties window (by pressing F3) to assign it to appropriate field.
For more information, select the following links: