There are three goals we can attain by a generic call interface:
A direct use of a library package is a big advantage. Things can be very simple to users who have gotten a library package of a driver or a program subroutine. They just have to write the description of the interface in another language they are familiar with.
A generic call interface may glue the functionality of a high level program executer with the ability of a call to low level code snippets.
The use itself of a call is as simple as calling every function, and will be executed by the normal REXX calling mechanisms by either using the functional kind or the procedural kind. This is standard.
The description of the external function will use stem techniques already used since the beginning. The different stem parts will describe the parameters to a function or procedure.
The descriptive part of the interface will be added to the well-known RXFUNC... SAA interface.
It is currently the time for good software to come back into mind. DCF77/GML is back as HTML. Unix shows in different flavours like BeOS, Linux, and Sun OS its advantages. Last not least the mainframe technique renascents.
REXX has a good chance to reenter the market if a useful and needed technology can be introduced. The object orientation has been integrated and even the connectivity to other languages has happened. I think it is a good idea to fill the gap which is between high level requirements and low level support in a user friendly way.
REXX may become again one of the most powerful script languages, and it may play a prominent part.