I've used the same format as you mentioned, usually for non-public-facing modules. Sometimes it starts with "YYYYMMDD", then "YYYYMMDD.XX" if needed. Every ver

I've used the same format as you mentioned, usually for non-public-facing modules. Sometimes it starts with "YYYYMMDD", then "YYYYMMDD.XX" if needed. Every version potentially breaks backward compatibility, regardless of versioning standard (semver, calver, or anything else). It's the responsibility of the module consumer to have tests and ensure its own functioning. I do find semantic versioning useful for public-facing modules/interfaces, to indicate (or infer from the consumer side) the intended compatibility. In practice, though, sometimes patch versions break things, or major version upgrades work fine without any changes. So the consumer still needs to be responsible for ensuring compatibility - not much different than calendar versioning.