Starting from Octez release 15.0, the names of the Octez binaries start with "octez-" and do not include any protocol number (e.g. "octez-client", "octez-node", "octez-baker-PtKathma" instead of "tezos-client", "tezos-node", "tezos-baker-015-PtKathma"). Occasionally, some legacy names ("tezos-*") may still be used in the documentation.
As explained in the Tezos Software Architecture, the shell is the rest of an Octez node when excluding the protocol; in other terms, the “blue octopus”.
The following pages describe the principles underlying the shell design and implementation.