axiom schema
a formula in the metalanguage of an axiomatic system in which one or more schematic variables appear
axiom schema of replacement
in set theory, the axiom schema that the image of a set under a definable class function is also a set
axiom schema of specification
axiom schema
axiom schema of predicative separation
in set theory, the axiom schema that a subset of a set exists if it can be defined without reference to the entire universe of sets