...system
Currently, versions of P/FDM based on both Quintus Prolog and SICStus Prolog are supported.

...query.d
We use the convention that files containing data manipulation programs written in Daplex have the suffix ``.d''. The compiler, however, does not recognise this suffix, and the full filename must always be given.

...getentity/2
Notice that for each Prolog procedure we give the mode in which it should be used by specifying which of the arguments must be instantiated on entry to the clause (those prefixed by a `+' symbol), which must be unbound variables (those prefixed by a `' symbol) and which may be either instantiated or uninstantiated (those prefixed by a `?' symbol).

john@
Fri Jan 13 15:22:47 GMT 1995