The last tab "Change Log" is intended to document who has changed what in the Use Case / Case Study. You can also add/edit the version number so that it is always kept up to date.
The version number consists of four digits, each separated by a dot. A distinction is made between the major and minor release as well as the addendum and the corrigendum.
The version number is adjusted mainly when the use case has been edited. The first number (major release) stands for major and drastic changes or adjustments to the document. The minor release number is adjusted if minor changes or extensions have been made. The Addendum is changed if the Use Case has been improved in some way. Finally, the Corrigendum, which documents minor improvements (e.g. spelling errors). More: https://technical.buildingsmart.org/standards/ifc/ifc-schema-specifications/
In Class you can choose a type of change from the dropdown list and describe it in the text description box.
To the next step
Save your edits. If you're finished with your creation you're ready to publish it. Switch to the tab "Publication" for the last step.