The Object Server Communications Area (OSCA) user class is used to communicate between an OpenROAD client and an OpenROAD Server application. An instance of this class must be passed using BYREF whenever a GSCP is called. This passes a context token from client to server and errors from server to client. A system variable of this class called OSCA is available.

The following diagram illustrates communication between an OpenROAD client and an OpenROAD Server application:

For information about OSCA in an OpenROAD Server application, see uc_osca (OpenROAD Server).