This part is where both a designer and developer should feel comfortable again! A Publication is where the Structurals (and all other MPS parts) are being combined to something that actually functions and can be experienced by a user.
Publications will call all the parts of the page (e.g. header, main section and so on) and display it as a complete page.
For designers there’s only one word that’s need to be said is: “mockup”! As we did a lot of work in the previous steps the word “mockup” will be more like “combine”. Combine previously made Pieces into pages (according to the wireframes or sketches) and finish them to deliver pixel precise designs, so developers know what to build.
It’s up to the developer and relative to the chosen CMS how to implement this – it’s a possibility not to use this MPS part and make custom calls to load the Structurals to be more efficient with files but you will loose some flexibility when making changes when needed.