The different projects maintained by the Lino Team depend quite strongly on each other. This is why we adopted a date-based versioning system.
Date-based versioning is similar to what Ubuntu uses: "Ubuntu releases on a time based cycle, rather than a feature driven one. Sometimes this can generate confusion, especially when people ask for a new feature to be added." (ubuntu.com)
For us, "Version 16.10" means "The version we started to release in October 2016". If a particular project decides that a bugfix release is needed, then they would call it 16.10.1 (and so on).
Note that months before September should be numbered 1 to 9 and not 01 to 09 because otherwise setuptools will normalize them and issue a UserWarning. (Setuptools issue 308).