Two code formats
BMW reports generic SAE J2012 codes (P/B/C/U) and its own 4- and 6-hex manufacturer codes. Both describe the same faults; the hex codes carry BMW-specific detail.
Severity, not just text
BeeEmUu tags every code advisory, service-soon or stop. A misfire code is not the same urgency as a headlight washer relay.
Look one up
Use the DTC decoder for a single code, the known-codes browser to search the catalogue, or the featured index for full write-ups.