Asymmetric Perspective

A Binary Association has two Perspectives. If you are using a subject-verb-object language like English, it is tempting to use the terms 'active' and 'passive' to distinguish these Perspectives. For example, the phrase pair configures / is configured by suggest an active and passive phrasing that might be applicable on any Binary Association.

But English is only one language and this scheme might not work so well in, say, Japanese.

So we just use the arbitrary names T and P (think Terrance and Philip from the SouthPark cartoon).

The important thing is that we can refer to each Perspective uniquely.

For example, Folder contains File is a distinct perspective from File is contained within Folder. We could name the first side T and the second P or vice versa.