Flag a recorded length below 10 cm OR above 20 cm. The endpoints 10 and 20 stay unflagged. This is a review policy, not a limit on valid crate sizes. Compare the recorded and independently checked lengths: agreement means a correct record in this invented exercise; disagreement means a recording error. A flag can be a false alarm, and an unflagged record can still be wrong. Treat the supplied independent checks as reliable here; real measurements can be uncertain. A missing check leaves correctness unknown.
Worked example
For a different band, 50 to 60 cm, a record of 64 cm is flagged. An independent check of 64 cm agrees, so the record is correct: a false alarm for an error. A record of 55 cm is not flagged, but a check of 56 cm disagrees: the rule missed an error.
Evidence file
Invented crate records (recorded length / independent check): A: 8 cm / 8 cm. B: 24 cm / 18 cm. C: 14 cm / 15 cm. D: 20 cm / 20 cm. E: 10 cm / missing. Apply the below-10 OR above-20 review rule to the recorded length, not the checked length.