The document is a workshop manual that provides information on servicing the 03-M-E3B, 03-M-DI-E3B, and 03-M-E3BG series diesel engines. It covers general information, the engine mechanism, and servicing procedures. The general section includes identification, maintenance, and special tools. The mechanism section describes construction and functions. The servicing section provides troubleshooting, specifications, torque values, adjustments, assembly/disassembly, and other procedures.