These are the javascript files containing all the functions that build the menu and drive its behavior. They are named awmlibX.js and reside inside the "awmData-mainmenu" directory which is created upon the Compile Menu process.
Their input is the compiled menu file (mainmenu.js). Therefore, the mainmenu.js represents the definition of the compiled menu whereas the awmlibX.js javascript libraries constitute the engine that generates the menu based on its definition.