**** The function process-coding-system tells you what<BR>
coding systems(s) an existing subprocess is using.
The value is a cons cell,
 (DECODING-CODING-SYSTEM . ENCODING-CODING-SYSTEM)
where DECODING-CODING-SYSTEM is used for decoding output from
the subprocess, and ENCODING-CODING-SYSTEM is used for encoding
input to the subprocess.
<P>