About
Daylight Savings Time are seasonal time adjustments for economic and political reasons.
They are known as:
- civil time
- or daylight time
The Local time may change for political or economic reasons due to daylight.
They are political divisions of the earth's surface that allow the convention that time is measured the same at all locations within the time zone, regardless of the precise value of sun time at specific locations.
Example
The time zone Europe/London is:
- but in DST known as the British Summer Time (BST): UTC+1
Rules / History
The rules are stored in the timezone databases.
The zone and rule lines reflect the history of DST.
Example:
# Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S
Rule US 1918 1919 - Mar lastSun 2:00 1:00 D
Rule US 1918 1919 - Oct lastSun 2:00 0 S