RBX.lua.DataModel (Service)
From Legacy Roblox Wiki
DataModel
The DataModel is the keystone of roblox's structure. It houses all of the services such as the Workspace and Lighting in a game. (With the exception of the "gameSettings") It even contains hidden services that Roblox Studio uses.
The DataModel, or as you probably know it as the "game" that you index in your scripts.