Cargo has its own interpretation of semver: first non-zero number is the major version, so v0.6 is like v6.0.0 and v0.7 is like v7.0.0. Then each major version

Cargo has its own interpretation of semver: first non-zero number is the major version, so v0.6 is like v6.0.0 and v0.7 is like v7.0.0. Then each major version is treated as a separate crate, as if it was cortex-m-v6 and cortex-m-v7.