If you raise a support request that concerns a released course, you may be asked to provide us with the course version number.
This is a unique number generated by the system when the release is made. It can be found on the Release page, under the title of your Project:
The version number increases each time a course is released. A course that has only been released once will show a version number of 1. A course that has been re-released once will show a version number of 2 and so on. A course that has been re-released using the Retain setting will cause the version number to go up in decimal increments. For example, Version 2 will become Version 2.1.
You can also refer to this value in an analytics data export from Your Data to see which learners have taken which version of a course. You can read more about this in Analyzing results from Your Data.