The timber from the old station

An original account of an invented cataloguing task.

During a clear-out at a local railway society, Leila found a dark wooden beam with an old label tied to it. The label read, “From the station footbridge.” Leila initially recorded this origin as definite. Before completing the catalogue, however, she compared the beam with the only surviving maintenance sketch of the bridge.

The sketch showed only the north half of the bridge. A separate note stated that the south half had once been repaired using timber cut on site, but gave no measurements. Leila also noticed clean saw marks across one end of the stored beam, suggesting that it might have been shortened after its removal.

Leila changed the catalogue entry to “possibly from the station footbridge”.

Explain two ways the measurements challenge Leila's original entry and two reasons why the beam's origin cannot be settled with certainty.