What is "back ventilated"?

I find that the name of a German Standard DIN 18516 is

"Back ventilated, non- loadbearing, external enclosures of buildings, made from tempered safety glass panels. Requirements and testing"

May I ask what is the meaning of "back ventilated"?

Thanks very much.

I have read and I agree to glassonweb.com's Terms of Use, including Privacy Policy and Cookie Use.