There is no naming protocol, like Microsoft went from Windows 8 to Windows 10 skipping Windows 9, I can chose to go from 0.09 to 0.1 and not 0.10 since from that point I will move linear to 0.2, 0.3, 0.4 and if need be 0.4 chapter B????
The only thing that is common is major updates are whole numbers like 1.0 so if I was at 1.3 and did a major update I would call it 2.0.
Personally, I prefer a build number in hexadecimal (e.g 11BCF), this should be incremented very regularly. And then for customers a simple 3 digit version number, i.e. 1.1.3.
1.2.3 (11BCF) <- Build number, should correspond with a revision in source control
^ ^ ^
| | |
| | +--- Minor bugs, spelling mistakes, etc.
| +----- Minor features, major bug fixes, etc.
+------- Major version, UX changes, file format changes, etc.