My company is a little odd in that we use the first 2 numbers as the "major release". The first number is the 2 digit year, and the second number is the release of that year, so for a "24.2.1.3" release, "24.2" is the major, ".1" is the minor, and ".3" is a patch. All of this is internal, most of our customers use our service to present their web sites, so this is mostly for our internal teams to keep track of what version each of our clients are on. Even for those clients that host their own sites still use our support teams, so knowing what version of the software they are on is critical to us and them.