Over the years I've stuck fast to a possibly self-invented rule that enumerating pairs of things in an out-of-order fashion requires a "respectively":
…where x, y, and z are "ecks", "why", and "zed", respectively.
But I begin to tire of this redundant usage where it's clearly obvious (or is it?) that the pairs match up n-to-n in the lists.
Is this rule I follow a real rule? Can I drop it in what seem to me, the writer, to be patently obvious cases?