Dan wrote in asking what is that little diamond mark on his tape measurer at 19-3/16 inches?
Look further down the tape and you will see it repeated every 19+ inches, always at some imprecise measurement, not really a multiple of 3/16 of an inch. Finally when you get to 8 feet it is dead on.
In fact if you divide 96 inches by 5 you will get 19.2 inches.
These marks are for laying out 5 engineered flooring trusses per 8 feet, like those wooden I beams.
Studs and traditional floor joists are usually either 16 or 24 inches on centre, and every 16 inches on the tape is marked with a triangle. Since engineered floor joists are stronger than solid wood, you get away with one less joist every 8 feet, so every 19.2 inches is marked out with a diamond.
It is referred to as a 'truss mark'.