To some extent we have waved our hands over the semantic distinction between a period of time and an event, lumping the two together as an interval.
Consider two data elements, dateOfBirth and lifespan.
· 2001/2015 means that the person was born during one of the years 2001, 2002, …, 2015. (Or you could say, sometime during the period beginning in 2001 and ending in 2015. Some like the first characterization because this is expressed with year precision but to me these say exactly the same thing.)
· 2001-06-06/2005-10-10 means that the person was born some day between 2001-06-06 and 2001-10-10 (inclusive).
· 2001/2015 means the person lived from 2001 to 2015.
· 2001-06-06/2015-10-10 means the person lived from 2001-06-06 to 2015-10-10.
(For lifespan, nevermind that some other application might define two elements, dateOfBirth and dateOfDeath; in this example a single element represents the span of time that two separate elements in a different application might represent the start and end of.)
There is an element of precision in both (1) and (2) but I don’t want to talk about precision now. What I want to talk about is the fundamental difference between (1) and (2): The first is an event; the second a period of time. (The first, an event that takes place in the period of time represented by the interval, but an event nevertheless and not a period of time.)
I have always maintained that whether 2001/2015 represents a timespan or a period during which an event occurred is application dependent; it depends on the semantics of the data element for which it is a value. 8601 (Part 1) is completely silent on this issue (definition -time interval: part of the time axis limited by two instants). Bibliographic applications use the interval form for both purposes.
Why do I bring this up?
One of the comments on the recent draft suggested the use of:
“..” for representation of an unspecified value that is “between” two dates (inclusive), such as “2015-01-22..2015-04.20”.
And the comment said:
This is not the same thing as a closed interval of “2015-01-22/2015-04-20”.
I am arguing that it is the same. (Or rather, that the interval form may be used for either, and so the suggested additional form is not necessary.