A lookup type is a static list of values. These lists can be referenced by activities and by item type, message or activity attributes. For example, an activity can reference a lookup type for its possible result values, while a message attribute can reference a lookup type as a means of providing a list of possible responses to the performer of a notification.

When you define a lookup type, you associate it with an particular item type. However, lookup types are not item type specific; when you create an activity or an attribute, you can reference any lookup type in your current data store, regardless of the item type that the lookup type is associated with.

Because lookup types can be referenced from multiple item types, the internal name and the display name for a lookup type must both be globally unique across all item types. You may find it useful to include a prefix such as the item type name to ensure that the lookup type internal name and display name are unique.