The seat Material"Uni" taking the german translation means that it is all the one material and not part leather part material
The 30B is for Dunkelblau(dark blue) carpet
Your JMS is actually JM5 and means Blue/Blue heres the link , go to page 287 sames codes on an 84-86
http://www.porsche.com/all/media/pdf/originalparts/de/D_911_86_KATALOG.pdf
DG I know relates to the Car as a whole but I donīt know what the individual Letters signify. Iīve seen a DP( donīt know what it meant either)