Unknown Space = C1 to C3
Dangerous Unknown Space = C4 and C5
Deadly Unknown Space = C6


Second hint - Wormhole colours

Blue with green highlights = C1
Blue with blue highlights = C2
Silver/Grey = C3
Copper/Green = C4
Light brown = C5
Red/Brown/Black = C6

Admittedly C1/C1 is hardest for the untrained eye. But you want to live in the void, you get trained.


Last hint if you're already inside the WH - Region

R1 - R3 = C1
R4 - R8 = C2
R9 - R15 = C3
R16 - R23 = C4
R24 - R29 = C5
R30 = C6

For C1 to C4, the start region is the class squared. C5 is 1 off, and C6 is easily remembered as the last region.