category(Category)
category(Category,
    implements(Protocols))
    
category(Category,
    imports(Categories))    
    
category(Category,
    implements(Protocols),
    imports(Categories))
Starting category directive.
category(+category_identifier)
category(+category_identifier,
    implements(+implemented_protocols))
    
category(+category_identifier,
    imports(+imported_categories))
category(+category_identifier,
    implements(+implemented_protocols),
    imports(+imported_categories))
:- category(monitoring).
:- category(monitoring,
    implements(monitoringp)).
:- category(attributes,
    implements(protected::variables)).
    
:- category(extended,
    imports(minimal)).