where the thread was left
You do not start over. Each return picks the thread up exactly where it last went quiet.
for the returning reader
Your archive is not restarted; it is resumed. The pattern you were reading last time is still the pattern to read.
for the new reader
Nothing to install. No archive to rebuild. The instrument is already made; you supply the evidence.
Sign in to resume, or begin — either way, the investigation continues.