According to an official source, Polkadot (DOT) has released a parachain road map. The roadmap is divided into multiple stages. Compared with the previous stage, each stage represents deliverables of another set or iterations on black-box components.
Phase 0 is the "MVP," which is also the initial phase. This is a parachain without slashing (completely secure) or cross-chain message passing. It is basically the registration and verification of a properly functioning PoC. Phase 1 is "fishing and slashing," which marks the progress of parachain security. Once completed, the parachain is a mature and secure aggregation primitive in cryptoeconomics. This stage also includes the implementation of XCMP, but it has not yet been fully activated. Phase 2 is "messaging," which marks the delivery of cross-chain messaging, including almost everything remaining in the XCMP part.