There is this from the big vw porsche book (DGVWP)
QUOTE
"vorhandene Löcher" = existing holes
"zu bohrende Löcher" - holes that need to be drilled
"zu verpfropfende Löcher" - holes that need to be plugged
"Hohlraum-Versiegelung - sinnvoll nach jeder echten Restaurierung" = cavity-sealing - useful after any real restoration
The factory manuals say just "after the completion of each body panel, all seams and welds must be sealed with VW D 17 sealing compound."