EST5EDT4,M4.1.0,M10.5.0

      This sample TZ specification describes the rule defined in 1987
      for the Eastern time zone in the US:

      o  EST (Eastern Standard Time) is the designation for standard
         time, which is 5 hours behind UTC.

      o  EDT (Eastern Daylight Time) is the designation for summer
         time, which is 4 hours behind UTC. EDT starts on the first
         Sunday in April and ends on the last Sunday in October.

      Because time was not specified in either case, the changes
      occur at the default time, which is 2:00 A.M. The start and
      end dates did not need to be specified, because they are the
      defaults.