 Since ZF is entirely immersed in this theory, it is clearly serviceable for the usual classical applications. The Frege natural numbers are not definable in this theory (except for 0 and 1); it is better to work with the finite von Neumann ordinals. The ability to prove strong results about large cardinals using the properties of the proper class ordinal suggests that the superstructure of large sets can be used for mathematical purposes as well. Familiarity with techniques of topology of \(\kappa\)-compact spaces would be useful for understanding what can be done with the big sets in this theory.