OptionalkeepSpares named snapshots — those the user gave a description — from erasure, and leaves them
out of the count as well, so the limit governs the automatic snapshots alone. Omitted, it
falls back to the revisionIgnoreNamedSnapshots option.
OptionalsnapshotsHow many snapshots to keep per note, standing in for the revisionSnapshotNumberLimit option
for this run. Negative keeps every snapshot (nothing is excess), zero keeps none; omitted
falls back to the option itself.
A note carrying a valid #versioningLimit follows its own label instead: that is a policy set
on the note deliberately, and a one-off answer to the global setting does not overrule it.
How far "Erase excess revision snapshots" should go. Both fields are optional: left out, the operation behaves exactly as the automatic trimming that runs after every saved revision.