Universal Send Data to Virtual Terminal Usage

While it is possible to open and close a virtual terminal session with a single invocation of UNVVTSND, that is not a realistic scenario. To perform work of any significance with UNVVTSND, multiple instances of the command are required.

Typically, there will be one command instance to open a virtual terminal session, followed by a series of command instances to perform some work in the session, and then a final command instance to close the virtual terminal session.