LOGIC ISSUE: phagophore assembly site membrane

[ValWood]

I don't understand this term.

The "phagophore assembly site" is defined

Definition | Parents
Punctate structures proximal to the endoplasmic reticulum which are the sites where the Atg machinery assembles upon autophagy induction.

so , how does an assembly site have a membrane?

Note also that these terms are not related to phagophore, so it isn't clear what the membrane being referred to belongs to?

It must be a membrane of some structure?

[ValWood]

This is how PomBase annotations look:
All of the inferred annotations are to "assembly site membrane"