The S3 interface to IDL is still experimental. We really haven't had
too many people use it enough to chase out many bugs...there many be
plenty of bugs hiding in there, we just haven't seen them yet...

Most of the interface is one way, i.e. you can start an IDL server in
the background, you can send data to the IDL server, you can send
commands to the IDL server, and you can kill the IDL server, you just
can't get data from the IDL server (its being worked on, but its a
*LOW* priority item, unless someone needs it)

The following interface routines can be called from the PCT level:

a:initialize_idl_server:;   !Starts the idl server and establishes
                            !client/server communication links.
                            !does not accept any parameters yet, 
                            !eventually it will accept the hostname
                            !for the server, and a server id number.

b:send_dataset_to_idl: ds1, ds2, ds3, ...;
                            !accepts any number of datasets to be
                            !passed to IDL. Creates an IDL variable of
                            !the same name, type, and size

c:send_command_to_idl: "command1", "command2", ...;
                            !accepts any number of IDL commands. A
                            !command can either be a CHAR dataset
                            !(one dimensional) or a string literal.

d:shutdown_idl_server:;     !disconnects communications and shuts down
                            !the idl server.
                            !does not accept any parameters yet, 
                            !eventually it will accept the hostname
                            !for the server, and a server id number.