JodaOrg/joda-time — pull request #206 by wyegelwel (2014-11-16 20:59:41+00:00)
Title: Create interface 'StandardPeriod' to make relationship between Periods explicit

The classes Duration, Seconds, Minutes, Hours, Days, Weeks all provide methods to convert to any of the others. 'StandardPeriod' makes the relationship between these classes explicit.