The SubsetAttribute class is used to indicate that the collection is a subset of the parent collection. The library uses the DatabaseObjects.Parent.DistinctValue property to determine the value to filter this table by using the field name specified in the attribute. For example if the collection was a set of InvoiceLines then the table would filter on the InvoiceID in the InvoicesLines table using the InvoiceID from the parent Invoice object. To further customer the subset (i.e. make it conditional) simply override the Subset function and do not specify a SubsetAttribute.

public class SubsetAttribute : Attribute

Public Class SubsetAttribute _
	Inherits Attribute

public ref class SubsetAttribute : public Attribute

<Subset("InvoiceID")>
Public Class InvoiceLines
    ...