Any single Open Client interface maps an application server application to a series of object types, as shown in the following table.

Table 1. Objects in an Open Client interface

Object Type	Occurrences	Description
AppObject	One required per application	Encapsulates zero or more external ABL procedures as directly callable methods and zero or more ProcObjects as class factory methods
SubAppObject	Zero or more per application	Encapsulates zero or more external ABL procedures as directly callable methods and zero or more ProcObjects as class factory methods
ProcObject	Zero or more per application	Maps to a persistent, single-run, or singleton procedure that encapsulates one or more ABL internal procedures and user-defined functions as directly callable methods