About forms with subcollections

A subcollection is a 'child' collection whose records (rows) are associated with and dependent on the items in the 'parent' (primary) collection. Subcollections are considered the primary mechanisms for defining hierarchical, parent-child data relationships on forms. Subcollections implement one-to-many relationships between collections.

To implement a form with a subcollection, you must bind a grid component to a subcollection property. This property is defined in the parent IDO as a child IDO that is filtered from the parent IDO. You can bind individual properties of the subcollection to grid columns or other form components.

When using subcollections, keep these limitations in mind:

• You can only have one level of subcollections (that is, parent-child collections). In other words, a subcollection cannot in turn have its own subcollection.
• Subcollections must be bound to Grid components.

  This is in contrast to top-level collections that can be bound at the form level, and not necessarily to any one (type of) component.

Examples of system forms that use subcollections include the Users form, the Background Task History form, and the Event Handlers form.