It uses a currently undocumented command in the Advanced Layout Options, but it is available for use. It works like the <!--System:Menu:xxx--> commands in the layout.html and the <!--Menu:XXX--> command in the menupage.html files.
Combining both of those, we get "Embedded Menus" using the <!--System:StartEmbedMenu:XXX--> command, allowing you to cusomize the approach of each menu, if you wish.
In <!--System:StartEmbedMenu:Menu--> the highlighted part is the Category of the menu, such as "Resources", "DKP", or "Links" as examples.
The rest of the code between the <!--System:StartEmbedMenu--> and <!--System:EndEmbedMenu--> commands work just like the code in the Menupage.html.
Using these functions, it's technically possible to make your layout without using the menupage file at all, but in most cases, it's more convenient to use the menupage for a lot, while using the Embedded Menus for special menus (like the menu across the top on the PiaS layout).