a. AFTER, BEFORE, and ON may be used with date expressions at any level of granularity; use BETWEEN only when a date range cannot otherwise be expressed accurately.
"yesterday" [where DD is 03/27/87"]
ON 260387
"next month" [where DD is "06/29/87"]
ON 0787
"in the fall" [where DD is "07/03/87"]
ON FA87
"in the next two days" [where DD is "06/29/87"]
BEFORE 010787
"sometime in April" [where DD is "12/16/87"]
ON 0487
"sometime since April" [where DD is "12/16/87"]
AFTER 0487
"between 10 and 12 July this year" [where DD year is 1987]
BETWEEN 100787 120787
b. If (a) a calendar (i.e., knowledge of more than just how many days there are in a month) would have to be used to determine exact date or (b) the date expression is too vague to be mapped directly onto a normalized date, use "BEFORE|AFTER <date-derived-fm-DD-date>" as fill, even though this normalization will lose a lot of the meaning:
1. Cases that would require a calendar
"[last] Saturday" [where DD is "04/27/87"]
BEFORE 270487
"the 30-day cooling off period ends 12:01 EDT Saturday" [where the date fill is supposed to represent the *start* of the cooling-off period, and where DD is "04/08/87"]
BEFORE 080487
2. Vague date expressions
"[will continue...] this week" [where DD is "07/15/87"]
AFTER 150787
"two weeks ago" [where the date fill is supposed to represent the interval starting two weeks ago, and where DD is "08/28/87"]
BEFORE 280887