Part of it is sequential, part of it is alpha-numeric:
I do not have a X-T2, so I cannot answer your question, but as I recall you have various backup options you set for the two slots that affect what happens. Someone over in the X-T2 forum should be able to help you.
Hello. I received XF 18mm f1.4 today. It feels like at least one of the elements inside is loose. When I flip the lens 90 degrees I can hear it drop back. But once I turn the camera on I don’t see this behavior. Is this normal? If yes, I like to learn what’s causing it. Thank you.