The user interface has four prompts
:
``rfi-p;SPMgt; '' or ``rfi-l;SPMgt; '' is displayed when the
queries are sent to the interpreter and its database, while
``rfe-p> '' and ``rfe-l> '' show that the query, which
is a valued conjunction of 
literals,
will be emulated after compilation.
The suffix of the prompt is ``-p;SPMgt; '' or ``-l;SPMgt; '',
respectively, when the system is running in PROLOG or LISP
style (see [Her92]). The code obtained is stored under
the name main, the data structures for the variables in
the query are created and their names and locations are
memorized to get the variable names when the goal succeeds.
Finally the emulator is called, producing failures or returned
values with possible variable bindings. When a goal succeeds,
the results are printed; backtracking is invoked if the user's
next input is more so that the next solution may be computed.
When spy is enabled, the query's compilation is shown and the
GWAM is set into debugging (interactive or non-interactive single-step)
mode. With nospy this feature is turned off.