3 0 Filter-only sentinel. A LOG event must not use this value. Message text was truncated to the bounded on-wire buffer. Bounded human-readable runtime log emitted by every Kaptan logging macro, including error. The receiver needs only level, flags, and the valid UTF-8 text prefix. MAVLink framing, bounded admission, DMA, and retries remain platform-owned. Kaptan wire level. TRUNCATED=1. Receivers ignore unrecognized bits. Number of valid UTF-8 bytes in message; at most 160. Bounded UTF-8 message bytes. Bytes after message_length are zero.