Every date format HTTP defines is read, the preferred one and the two obsolete ones alike, and no other: a date
in some other notation, an ISO 8601 one included, is reported as missing rather than guessed at, leaving the
consumer to decide what to make of it. So is a date naming no real day, a thirtieth of February among them.
Where a format states a two-digit year, it is read as the most recent past year ending in those digits rather
than as a date more than fifty years ahead.
A leap second, which the grammar admits, rolls over into the following minute rather than being reported as
missing.
The instant value states, in milliseconds since the epoch; undefined if value is missing or doesn't
state a date in one of the three formats HTTP defines
Parses a date field value.
Every date format HTTP defines is read, the preferred one and the two obsolete ones alike, and no other: a date in some other notation, an ISO 8601 one included, is reported as missing rather than guessed at, leaving the consumer to decide what to make of it. So is a date naming no real day, a thirtieth of February among them.
Where a format states a two-digit year, it is read as the most recent past year ending in those digits rather than as a date more than fifty years ahead.
A leap second, which the grammar admits, rolls over into the following minute rather than being reported as missing.