_manifesttriomphe.ymf -

: It acts as a set of instructions for the game to pre-load specific models or interior assets before the player arrives at that location in the world.

: In GTA V, simply placing a custom map file ( .ymap ) in the game directory isn't always enough. The _manifest.ymf file lists all the dependencies and "Archetypes" required by that map. _manifesttriomphe.ymf

Are you trying to with a specific mod, or are you looking to create your own manifest using CodeWalker? : It acts as a set of instructions