When you select a value from a list, the form may bring back data that is dependent on the selected value. For example, if you select a field named Product, then a list in a Module field may be refreshed, showing only the valid entries for the Product selected. These are termed Allowed Value Lists and are maintained by the administrator.
Allowed value lists are an efficient mechanism to make certain that you can only add valid data to a form. In the case just defined, the Product field is termed the parent and the Module field is termed the child. The parent and child fields may not be select lists. They may also be selection tabs across the screen, or they may be pop-up lists. Pop-up lists are most frequently used when there are a large number of options to choose from, and some searching for the value may need to take place.
Allowed value lists may be chained together. You might see a chain which is termed grandparent --> parent --> child. An example might be Product Family --> Product --> Component. When you choose a value for Product Family, the Product list will only show the members of the Product Family. Similarly, when the user chooses a Product, the Component list will show only the Components for the selected Product.
These are only implemented infrequently by your administrator. In this case, when you encounter an allowed value list combination, all lists are initially popuplated with all values. You choose a value from any of the lists and the other lists are filtered to only show valid entries, whether they are parents or children.
