If this is the latest documentation it will need amending to reflect your post above.
https://github.com/triplea-game/triplea/blob/main/docs/map-making/reference/map-yml-file.md
I see 'version' is in the docs, that should be taken out.. The rest of it at a glance looks okay. Was there something else in there that needs updating? As far as YAML goes, it's a question of the differing formats. In the shorthand format, the quotes are needed so that YAML knows where the field ends. In the long-hand format, with 'map_name' on its own line, YAML infers the data type based on the first character of the value. So, it can tell the value is text, and YAML treats the rest of the line as text.
A lot of maps, map.yml format will be like mine, single player there appears to be no problem. However will the new 2.7 lobby work correctly?
There are going to be two servers! The lobby server and "support server". It was planned to have 3, {lobby, support, maps}, but maps & support were combined.
Immediately, the support server won't be able to index maps that have a bad map.yaml file. Those maps won't be listed as available for download. Locally, eventually the map will be invisible to the game itself. I think there is some flagging put into the code right now to use the old map loading system. In short, it will become a problem soon.
After the 2.7 launch, I have high on my list to try and provide a map indexing status page of some sort. I recognize that process is pretty opaque right now.
