Part VI — The tamper-evident seal

The locks themselves carry a tamper-evident seal — like the little sticker on a medicine bottle. If someone quietly weakens a lock (say, removes the part that blocks phoning out), the seal is broken and a routine check flags it. When another team borrows the Linux doorkeeper, they keep an identical copy and match its seal, so the two never quietly drift apart.

One honest word: a seal makes tampering obvious, not impossible. It tells you that something changed; it doesn't physically prevent a determined person from changing it.