Some Internet Service Providers and enterprises desire to be aware of more information about each packet, so that packets can be treated differently and efficiently. Packet-level differentiating can also enable flow-level and user-level differentiating. IPv6, with a large address space, allows semantics to be embedded into addresses. Routers can easily apply relevant operations accordingly. This document describes a framework that embeds semantics into IPv6 prefixes, so that network devices can treat packets based on these explicit semantics. This document also analyzes on the technical gaps for embedding complex semantics. This informational document only discusses usage of semantics in a Semantic Prefix Domain. It does NOT intent or suggest to standardize any common global semantics.