All data types are located in the DeltaEngine.Datatypes namespace. All data types are optimized for whatever they are used for most. For example Vectors, Matrices and Colors are used mostly in Vertex data structures and are as compact as possible (e.g. Color is just a uint), while still making external use quick and easy (e.g. Color can be created with 3 or 4 float values for R, G, B and optional A). Most operations are also heavily optimized for speed, especially all Matrix and Vector operations because they will be used a lot in inner loops for rendering, transformations, animations and bone calculations. In normal game code you don't have to worry about this, you can just use the normal operation methods. The optimized ones (with ref parameters) are only really needed for that extra bit of performance in animation and rendering code.