On Basilisk Station

the Star Kingdom of Manticore's history texts follow the convention of counting years 'Post Diaspora' (i.e., in T- years from the year in which the first interstellar colony ship departed Old Earth) as well as in terms of the local calendar.

The Kingdom's official reckoning of dates is based on the rotational and orbital periods of Manticore-A III, the planet Manticore. This calendar is used for all official records, the calculation of individuals' ages, etc., but doesn't really work very well for the seasons of any planet other than Manticore itself. Accordingly, both Sphinx (Manticore-A IV) and Gryphon (Manticore-B IV) have their own, purely local calendars, which means that a single star system routinely uses no less than four calendars (including standard reckoning). Needless to say, dateconversion software is incorporated into virtually every Manticoran computer.

The Kingdom's planetary days and years are:

The clocks of each planet count time in full 60-minute standard hours with an additional, shorter 'hour' called 'compensate' (or, more commonly, simply 'comp') to make up the difference. Thus, the planet Manticore's day consists of 22 standard hours hours plus a 27-minute-long comp, while Sphinx's day consists of 25 hours plus a 37-minute comp. Gryphon's day, like Manticore's, is 22 T-hours long, but with a comp of approximately 41.5 minutes.

The planetary week is seven planetary days long in each case, and Manticore's day is used aboard all Royal Navy vessels.

The official year of the Kingdom is 673 days long, with a leap year every third year. It is divided into 18 months, 11 of 37 days and 7 of 38, alternating for the first 6 and last 8 months, named (simply, if rather unimaginatively) First Month, Second Month, Third Month, etc. The Gryphon local year is also divided into 18 months (16 of 36 days and 2 of 37 days) with the extra days in Ninth and Tenth and one extra day in Eleventh Month every other local year. The Sphinxian year, however, is divided into 46 months, 35 of 39 days and 11 of 38 days (the shorter months fall in even-numbered months from Twelfth to Thirty-Second), with a leap year every 7 years. All of these calendars are reckoned in 'Years After Landing' (abbreviated A.L.), dating from the day (March 21, 1416 P.D.) the first shuttle from the colony ship Jason touched down on the present-day site of the city of Landing. Obviously, this means that each planet's local year is a different 'Year After Landing' from any of the others. Thus, Honor Harrington's orders to Fearless, dated Fourth 25, 280 A.L. (using Official Manticoran Reckoning, or the Manticore planetary calendar), were also written on March 3, 1900 P.D. (Standard Reckoning), and on Second 26, 93 A.L. (using the local Sphinxian calendar). This plethora of dates is a major reason Manticorans tend to convert time spans into T-years for comparison purposes.