Omnibus edition

An omnibus edition, or omnibus, is "a book containing multiple creative works by the same or, more rarely, different authors"; "a collection of shorter works, or shorter works collected with one previous book, may also be known as an omnibus." What it is for: "omnibus editions help consolidate longer series into fewer books," at a price "usually equal to or less than the price of buying each individual edition separately." The Chronicles of Narnia runs as one omnibus of all seven novels, The Lord of the Rings as one with all three volumes and six appendices, and comics publishers collect serialized runs the same way.

For a serial novelist the omnibus is the gathering format: what a web serial becomes as a collected edition, one volume per arc or the whole run, a separate edition with its own ISBN. Planning the split in advance is structuring a web novel into volumes.