Format information is currently only implemented for the ExtSaveData, SharedExtSaveData and SaveData archives, the information is stored in a file alongside the root folder of the archive.
This coincidentally fixes an issue about the PTM service failing to create its SharedExtSaveData archive due to the FS service not being initialized by the time the creating code runs.
Ideally I'd like to move each process to its own folder, and have a single file per process that registers the service classes, which would be in their own files inside that folder. Then each service class would just call functions from the process to complete the commands.
Lioncash