Perfectly normal space

Definition
A topological space is termed perfectly normal if it is normal and every closed subset is a G-delta subset ($$G_\delta$$).

Formalisms
Modulo the assumption of the space being T1, the property of being perfectly normal can be encoded as:

Closed $$\implies$$ $$G_\delta$$

Metaproperties
Any subspace of a perfectly normal space is perfectly normal.

Textbook references

 * , Page 213, Exercise 6 (definition introduced in exercise)