Ken Pizzini wrote on 1998-01-13 11:54 UTC:
There is a shade of meaning difference between the two: in non-technical situations the term "before" can be used to mean "up to and including", whereas "prior to" never seems to accrete the "including" meaning.
There was in the first draft of ISO 8601:1998 an annex C that tried to standardize the precise technical meaning of such terms. However it seems that this annex has been removed from the current second draft <http://www.cl.cam.ac.uk/~mgk25/8601v03.pdf>. The terms (as originally proposed in some CEN Medical Informatics working group proposal) were: Reference time interval: ----------------> AT ----------------> BEFORE -------> AFTER -------> DURING -----> INCLUDES ----------------------------------------> CO-CONTINUES ---------------------------> CO-PRECEDES -----------------------------> CO-STARTS ----------> CO-ENDS -----------> (Make sure you use a monospaced font to display the above!) It seems that this CEN proposal is somewhat restricted and incomplete, but the discussion here suggests that it might nevertheless be a good idea to have such a specification for technical discussion about temporal structures. Better proposals? BTW: The above proposal contradicts your interpretation of "before". Markus -- Markus G. Kuhn, Security Group, Computer Lab, Cambridge University, UK email: mkuhn at acm.org, home page: <http://www.cl.cam.ac.uk/~mgk25/>