Colour codes for 88 colours

I am looking at the colour codes Have seen the 88 colour, any idea what bit length is used for 88 colours? 3-Bit (2^3) | 8 | 8 (Primary) (000 to 111) 4-Bit (2^4) | 16 | 16 (Basic) (0000 to 1111) | 88 | 16 (Basic) + 4×4×4 (Cube) + 8 (Grey) 8-Bit (2^8) | 256 | 16 (Basic) + 6×6×6 (Cube) + 24 (Grey) 24-Bit (2^24) | RGB-Code has 24-Bit Format (Bits 0 to 23) 16,777,216 | 8 Bits Per Colour Channel (2^8=256) | Red[7:0]Grn[7:0]Blu[7:0] (256^3) | Hex FF is 255 (256 = 16*16)