l symbol definitions in the object file is registered
in the module object.
<B>Defforeign</B> is used to make entries to  C functions
to be called from EusLisp.
<B>Defun-c-callable</B> defines lisp functions callable from C.
C-callable functions have special code piece called <EM>pod-code</EM>
for converting parameters and transferring control to the corresponding
EusLisp function.
<B>Pod-address</B> returns the address of this code piece which
should be informed to C functions.

<P>
Here is an example of C