Typically each ontology file will be placed into its own module. For performance reasons it is often better to put multiple ontologies into the same module. Example: We have two files:

File 1:

:- module=m1.

:- import=m2.

B::A.

File 2:

:- module=m2.

C::A.

If we write

load "file1.obl" // module m1

load "file2.obl" // module m2

in the project file then we have two ontology objects and the extensional database contains the facts

B::A@m1.

C::A@m2.

If it is not required to access "m2" directly, then it is better to write

load "file1.obl" // m1

resolve <m2> = "file2.obl" // m2

In this case we have

B::A@m1.

C::A@m1.

in the extensional database (which will provide better performance).