2017-04-14 PMC Ukraine Mariupol v0.1 released.
These dev diaries for PMC Ukraine Mariupol started in 2022, however this terrain was initially created in 2017. Even the latest v0.2 release was done in 2017-10-24.
If you want to dig deep into the origins of Mariupol, check out PMC Real World Data Terrain MEGA Project in PMC Tactical forums. If you do read it, remember that you are reading part of history and so many things, plans etc have changed in 2022 when Mariupol dev diary page was created.
We also got Terrain Development (PMC ArmA 3) which looks like very quick summary type dev diary with all the terrains stacked into same topic, nothing like these specific detailed in-depth comprehensive ones being written in 2022.