How to describe relative dates (from/to fields)

When you create a new data source you are asked to specify the date range for the events (from date/to date). Sometimes the dates are absolute values, e.g. 2015-02-03, but quite frequently they are relevant to the current date and time. EventBlender uses underneath the PHP function strtotime to convert textual representations into absolute times, as shown in the examples below:

All absolute dates were calculated assuming the current date and time is 2016-04-30 13:02:35
Relative DateDescriptionAbsolute Date
now2016-03-08 13:02:35
today2016-03-08 00:00:00
today +24 hours2016-03-09 00:00:00
monday this week2016-03-07 00:00:00
sunday this week2016-03-13 00:00:00
monday previous week2016-02-29 00:00:00
sunday previous week2016-03-06 00:00:00
monday next week2016-03-14 00:00:00
sunday next week2016-03-20 00:00:00
first day of this month2016-03-01 13:02:35
last day of this month2016-03-31 13:02:35
first day of previous month2016-02-01 13:02:35
last day of previous month2016-02-29 13:02:35
first day of next month2016-04-01 13:02:35
last day of next month2016-04-30 13:02:35
+0 days2016-03-08 13:02:35
+7 days2016-03-15 13:02:35
-7 days2016-03-01 13:02:35
+1 week2016-03-15 13:02:35
-1 week2016-03-01 13:02:35
+2 months2016-05-08 13:02:35
-6 months2015-09-08 13:02:35
+1 year2017-03-08 13:02:35
-5 year2011-03-08 13:02:35
+1 day +1 week +1 month2016-04-16 13:02:35