Chevalley scheme

A Chevalley scheme in algebraic geometry was a precursor notion of scheme theory.
Let "X" be a separated integral noetherian scheme, "R" its function field. If we denote by formula_1 the set of subrings formula_2 of "R", where "x" runs through "X" (when formula_3, we denote formula_1 by formula_5), formula_1 verifies the following three properties
Originally, Chevalley also supposed that R was an extension of finite type of a field K and that the formula_15's were algebras of finite type over a field too (this simplifies the second condition above).