This is Zulu time for humans; UTC we can read and speak.
'Time' means both where the sun is relative to you - which is your local time, and a moment in the progression of time - UTC, the Coordinated Universal Time, or "Zulu Time" in navigation. It is always the same moment, the same Zulu Time, all around the world, based on the events that have happened vs. those still to come.
Two completely distinct meanings, yet we use the same language for both, HH:MM:SS, with trailing letters to indicate whether it is the local time of day- where the sun is now at that locale, like 4:00 o'clock Eastern Standard Time, or with a Z or UTC or GMT to indicate we are talking about the 0 hundred hours moment in time.
Our increasingly global world needs to keep these two notions distinct in people's minds, by using different notations:
Zebra Time replaces the hour number with a letter. 04:00Z becomes D:00. The time of day might be any time, such as 6:00 o'clock, depending on where you are at B:00.
This project provides the software for an easier way to relate and manipulate both kinds of time, or both people and computers.
Please see https://zebratime.org