MBC Instruction Set Architecture for the Unheaded Protocol Computer

This document defines the MBC (Monad Bytecode) Instruction Set Architecture for the Unheaded Protocol Computer (UPC). MBC is a 48-opcode, 32-bit fixed-width instruction set designed for execution within eBPF XDP programs. It provides computational capabilities for distributed packet processing using the Monad wire format, enabling deterministic network packet classification and transformation at the network edge.