Years ago, between jobs, I was working for an agency.
I worked with some suspended ceiling fixers for a while, just labouring sort of stuff.
Sometimes the dimensions they gave me for cutting the ceiling tiles at the edges and corners of the room were mixed metric and imperial, and/or ambiguous between millimetres and centimetres. Usually I looked at where they were and if it seemed confusing I asked, but they got one or two surprises.