We have a single example (used twice with slight differences) that shows use of dating attributes in a way I think may be inappropriate: <residence from="1857-03-01" notAfter="1857-04-30">From the 1st of March to some time in April of 1857.</residence> I don't like the combination of @from and @notAfter. As I understand (or at least imagine) it: @from and @to: indicate a range of dates during which something happened -- the thing happens during the entire range. <persName from="1940-10-09" to="1969-04-21">Lennon, John Winston <persName from="1969-04-22" to="1980-12-08">Lennon, John Winston Ono or <occupation from="1991" to="1994">Provost, Duke University For the *entire period* from 09 Oct 40 to 21 Apr 69 his name was "John Winston Lennon", and for the *entire period* from the day he legally changed his name (22 Apr 69) to his death (08 Dec 80) his name was "John Winston Ono Lennon". Similarly, Tommy Langford was Provost from 1991 to 1994. We don't know what day he became Provost or what day he stepped down, so the values of @from and @to are given only to year precision. Fair enough. (If we knew more, we could provide more precision.) @notBefore and @notAfter: indicate the earliest and latest endpoints for a single event to have occurred. Typically, but not at all necessarily, that event is measured in the precision of a single day. E.g. <death notBefore="1831" notAfter="1840"/> indicates that Mary Clarke [nee Carr] died sometime between those dates. She died on one day[1] during those days, she did not spend all 9 years in the throes of death. I think these notions of @from and @to indicating a *duration* during which something happened continuously, and @notBefore and @notAfter indicating endpoints within which range something happened at a given point, is borne out by the definitions in the tagdocs: - notBefore: specifies the earliest possible date for the event - notAfter: specifies the latest possible date for the event - from: indicates the starting point of the period - to: indicates the ending point of the period Thus my unease with the example <residence from="1857-03-01" notAfter="1857-04-30">From the 1st of March to some time in April of 1857.</residence> To me, the @from indicates that she lived there for a 1-2 month long period starting 01 March; but the @notAfter (at least, taken alone) implies that she lived there for one day[2] some day before 01 May. So I'm sure I don't like this, although I'm not sure how to solve the problem, i.e. how this information should be indicated. Possibilities include: * State explicitly in the prose what @from & @notAfter or @notBefore & @to mean. (To wit, an entire duration of vague length, specified by one endpoint and a point over which the duration did not extend.) * Indicate the duration with a start point and a duration, then indicate the (lack of) precision of the duration: <residence xml:id="R" from="1857-03-01" dur="P46D"> From the 1st of March to some time in April of 1857. </residence> <precision target="#R" match="@dur" atLeast="31" atMost="61"/> Don't like this as it sits, because it only works because we presume the unit @atLeast & @atMost refer to is days. Makes sense for this case, but if the dur= were "P1M15D" it would be less obvious. I presume if it were "P1.5M", one would have to use atLeast=1 atMost=2; i.e. the precision attrs apply to the lowest order component. So I guess we could make this work by making that the rule. * Fix <precision> so that it allows representation of precision (meaning the unit or number of significant digits to which a value may be measured reliably) rather than just precision (meaning vaguely how exact or accurate). Then <residence xml:id="R" from="1857-03-01" to="1857-04-15"> From the 1st of March to some time in April of 1857. </residence> <precision target="#R" match="@to" dur="P15D"/> or whatever. * Create new attributes (egads!) to mean exactly what we want. E.g., @fromAfter and @toBefore. * Don't fix it. Caveat encoder. People tend to know what you mean. Besides, what possible automated processing will handle this stuff? Notes ----- [1] Actually one second, but let's not go nuts. [2] Or only one second, but let's not go nuts.