In Modern English there are also special forms for expressing relative priority - perfect forms. Perfect forms express both the time (actions preceding a certain moment) and the way the action is shown to proceed (the connection of the action with the. indicated moment in its results or consequences). So the meaning of the perfect forms is constituted by.two semantic components: temporal (priority) and aspeetive (result, current relevance). That is why perfect forms have been treated as tense-forms or aspect-forms (come - has come; is coming - has been coming).
Members of these oppositions are not opposed either as tenses or as aspects (members of each opposition express the same tense and aspect). These oppositions reveal the category of order (correlation, retrospect, taxis).
Tense and order are closely connected, but they are different categories, revealed through different oppositions: comes – came; comes - has come. The fact that the verbals have the category of order (to come - to have come, coming - having come) and have no category of tense also shows the difference of these categories.
The meaning of perfect forms may be influenced by the lexical meaning of the verb (limtive/unlimitive), tense-form, context and other factors.