Thanks for the kind welcomes, all!

Unfortunately, Candy, I am not sure I get the connection between expire dates and the spatial concept of temporal duration... Maybe it is just some meaning nuance I am missing: is expiry used to refer to space distances too?

Come to think of it, it does imply a linear span - and time (probably inferring from man's experience with space?) is predominantly thought of in linear terms, in post-Modern ages that is...