Opaque data is composed of bytes of a fixed size that are not interpreted as they pass through the data streams. Opaque data bytes, such as handles, are passed between server and client without being inspected by the client. The client uses the data as it is and then returns it to the server. By definition, the actual data contained in the opaque object is not portable between computers.
The XDR library includes the following routine for opaque data:
Routine