/* Urbit time: 128 bits, leap-free.
**
** High 64 bits: 0x8000.000c.cea3.5380 + Unix time at leap 25 (Jul 2012)
** Low 64 bits: 1/2^64 of a second.
**
** Seconds per Gregorian 400-block: 12.622.780.800
** 400-blocks from 0 to 0AD: 730.692.561
** Years from 0 to 0AD: 292.277.024.400
** Seconds from 0 to 0AD: 9.223.372.029.693.628.800
** Seconds between 0A and Unix epoch: 62.167.219.200
** Seconds before Unix epoch: 9.223.372.091.860.848.000
** The same, in C hex notation: 0x8000000cce9e0d80ULL
**
** New leap seconds after July 2012 (leap second 25) are ignored. The
** platform OS will not ignore them, of course, so they must be detected
** and counteracted. Perhaps this phenomenon will soon find an endpoint.
*/
