Date range argument handler
Argument is based on ISO 8601 date duration and time interval standards
See http://en.wikipedia.org/wiki/ISO_8601#Week_dates for definitions of ISO weeks See http://en.wikipedia.org/wiki/ISO_8601#Duration for definitions of ISO duration and time interval
Argument expects a value like 2006-01-01--2006-01-15, or 2006-W24, or @P1W. Separate from and to dates or date and period with a double hyphen (--)
From and to dates in argument are ISO dates, but can be shortened and missing parts will be added. Omitted parts of ISO dates will be assumed to be the first possible (for the from date) or the last possible (for the to date) value in that time period.
The 'to' portion of the argument can be eliminated if it is the same as the 'from' portion Use @ instead of a date to substitute in the current date and time.
Shortcuts are available:
Use periods (P1H, P1D, P1W, P1M, P1Y) to get next hour/day/week/month/year from now Use date before P sign to get next hour/day/week/month/year from that date The ISO standard calls for a separator (--) between a date and the P, but the separator is optional between a start date and a period in this argument to make the result easier to read.
This module does not currently handle the option of using a period with an end date, only a start date followed by a period.