Option or requirement
The group exam format is used for oral exams, exam submissions only or exam submissions followed by an oral exam.
For either of these exam types the course manager can choose if the format is a group set-up or a mixed set-up. A mixed set-up lets you decide whether you want to attend as a group or as an individual.
Different set-ups:
Your exam might be a group exam (G) for both the ordinary and the re-exam or it might be a group exam for the ordinary and a mixed exam for the re-exam. Or it might be mixed for both the ordinary and the re-exam. It is stated in the course description what exam form and variation that has been chosen for your exam.