note 91977 deleted from datetime.modify by danielc

Note Submitter: tacker at php dot net ---- Do not use '[+/-]{n} month' to get the last day of the month. If you use '+1 month' on the first of the month, it sets the date to the next first of the month. This behaviour gives the impression, that php considers the length of a month, which is not true. Basically if you use '+1 month' it takes the month number, adds 1 and parses result as a new date. But if you use '+1 month' on the last day of a month, the result is unexpected as 2009-05-31 becomes 2009-06-31 which is an invalid date and then interpreted as 2009-07-01.