I thought they were issued these days in ebook format:
The Hitchhikers Guide to the Andrew said:
Stand from under
An archaic term used by the leader class of the species Homo sap.sapiens (called Officer) to inform a fellow H.sap that if they remain in the same geographical position, they are likely to suffer death or injury
Not standing from under may have the same result as standing in direct line of recoil. Actually, try not standing in direct line of recoil when working on the casing during harbour stations...there just ain't no place to hide!
Do not stand in a bight or coil either...common sense really.
Stand from under was also used to warn a miscreant that punishment was coming their way if continuing down the same route.