When dealing with vectors, it is also important to establish your frame of reference. Sometimes, though by no means always, there is a well-established conventi

When dealing with vectors, it is also important to establish your frame of reference. Sometimes, though by no means always, there is a well-established convention. When it is not, however, it can get verbose to encode into identifiers. It can also be tedious, as no-one needs to be reminded of it every time they read an expression. In these cases, documentation is the best choice.