The content validation before archiving depends if Tark4 is installed as part of GN4 / together with GNPortal, or it's a stand-alone archive.

Tark4 is installed as part of GN4 / together with GNPortal

Before archiving an edition, the archive process checks if there's a PDF of the each page, and if the original images exists on the volumes (disk folders).

Custom checks may be added too. See also Automatic content validation.

Tark4 is a stand-alone archive

The solution is custom, and checks depend on the current editorial system.