D-Time summary

D-Time could stand for Decimal Time, Diurnal Time or Day-Based Time. D-Time (DT) counts days¹ and days only. Time is given as fractions of a day, and the date is considered to be the number of days since a chosen point in time. This point in time is called the DT epoch² and has been arbitrarily chosen to be 13 July 1903 (midnight GMT). If nothing else is indicated DT is always given relative to the zero meridian at Greenwich. This is called DT
Global, or DTG.

DT gives the change in date as well as the time of day. This creates a problem as the date is changing unsynchronised with the Gregorian calendar. Therefore, DT can also be given relative to a DT time zone (DTB-K), so that the change of date occurs closer to the "ordinary" change in dates. This is good enough for human interaction, but can cause a problem for computers or records kept in both DT and Gregorian, hence the hack DT Local (DTL) that
gives D-Time relative to the traditional time zones.

In addition, there's the impractical DT apparent (DTAx) giving time relative to longitude x³, ideal for astronomers and those who feel the universe should revolve around them.

The ten DT time zones are 36 "regular" degrees longitude in width. DTB is centred around 180 degrees western or eastern longitude. DTC is 144°W(-.4), D is 108°W(-.3), E is 72°W(-.2), F is 36°W(-.1), G is (of course) 0°(0.0), H is 36°E(.1), I is 72°E(.2), J is 108° E(.3) and K is 144°E(.4), which brings us round to DTB at 180°W(+.5 or -.5).

The DT standard also opens for indicating dates relative to some time different from DT epoch. There are currently no such alternative epochs specified. At the time such alternative epochs are submitted and approved, they will be given an official code such as ADT, BDT,
etc.

Temporary or personally assigned epochs for entertainment purposes should be labelled in
prose⁴ and/or with the code DTR, meaning DT relative.