Why DMR repeaters use a Color Code, a number from 0 to 15, that your radio must transmit in order for the repeater to accept the signal. It works much like a CTCSS tone on an analog repeater: it keeps a repeater from being keyed by a co-channel DMR system on the same frequency. The color code must match what the repeater expects, and it is programmed into the radio's channel or codeplug along with frequency, offset, time slot and talkgroup.
Watch out The idea of a code that identifies the CODEC is tempting because DMR does use a vocoder (AMBE+2), but that is fixed by the standard, not signaled by the color code; nothing in DMR auto-programs your offset either.
Color Code = DMR's CTCSS. 16 colors (0-15), match it or the repeater ignores you.