Definition:Small Class

Definition
Let $A$ denote an arbitrary class.

Then $A$ is said to be small iff:


 * $\exists x: x = A$

where $=$ denotes class equality.

That is, a class is small if and only if it is equal to some set variable.

Remark
Small classes correspond to sets.

They are, however, distinct from set variables because set variables are arbitrarily chosen.

By All Sets are Small, all set variables are small classes.