Zone Language - Rules
We're in Unix world - lets do it in a text file with rules:
Rule US 1967 1973 - Apr lastSun 2:00 1:00 D
This rule is part of the 'US' rules family.
It applies to times between years 1967-1973, inclusive.
It applies to all years in this range (the '-' states that).
The rule takes effect on the last Sunday of April, on 2AM.
At which time we should add 1:00 hours to the local-time,
And we then change the variable-part of the abbreviation of the time-zone to 'D'.
Originally written by