Which VCF field do I use to specify a group in Android?

I'm creating a VCF file on my website. It works nicely with the export, and most data are being imported, but the group is not created or used on Android. I've tried using CATEGORIES and ORG. I also tried to look at KIND and MEMBER, but couldn't figure out how to use those, seems to refer to URI's and not a group name in the phone book. If I export a contact, it doesn't fill in the group in the contact. Which VCF field do I use to specify a group in Android?