Named windows, each written in the clock of the market it belongs to.
The zone is half the definition, not decoration. us-regular as a bare 1140
was unreadable as "09:30 New York", and it silently froze the US session at
whatever offset New York happened to have on the day the number was written,
so it opened an hour early for the five winter months. Written as 09:30 in
America/New_York it follows the exchange through both changeovers.
The bands are the same partition of the day as before, re-expressed: London
and New York keep exactly the instants they selected under DST (where the old
numbers were right) and gain the hour the old numbers lost in winter.
all-hours names no zone because it never reads one: an empty window
(start === end) short-circuits before any clock is consulted.
Named windows, each written in the clock of the market it belongs to.
The zone is half the definition, not decoration.
us-regularas a bare 1140 was unreadable as "09:30 New York", and it silently froze the US session at whatever offset New York happened to have on the day the number was written, so it opened an hour early for the five winter months. Written as 09:30 in America/New_York it follows the exchange through both changeovers.The bands are the same partition of the day as before, re-expressed: London and New York keep exactly the instants they selected under DST (where the old numbers were right) and gain the hour the old numbers lost in winter.
all-hoursnames no zone because it never reads one: an empty window (start === end) short-circuits before any clock is consulted.