derived_from(Original)option to load_files/2.
userif the file was loaded from the terminal or another unknown source. Options are the options passed to load_files/2. Note that all predicates to load files are mapped to load_files/2, using the option argument to specify the exact behaviour.
fileif the source was loaded from a file,
resourceif the source was loaded from a resource or
stateif the file was included in the saved state.