In our Joomla book library
we have the following notation for the version number:
For example, if the version number is 6.2.7.
6 - release of the main version, big changes
2 is the next majority level, changes have been added but not as big
7 - bug fixes. we have a lot of clients and this number can be very high, but we don't show the clients details about it, we fix it silently.