Named for the one tool that always finds true.
A plumb bob is the oldest precision instrument on a site — a weight on a line that uses gravity to find true vertical, and the fixed point everything else is measured from.
That is the platform in a single image. Datum takes the noise of thousands of documents and resolves it to one true point: the answer. Fittingly, to plumb something also means to get to the bottom of it — to fathom its depth.
And the name does the same work as the mark. In construction, a datum is the fixed reference every other measurement is taken from — the surveyor’s anchor, the drawing’s elevation zero. In Latin, it is literally a unit of data: the singular of data. The platform sits where those two meet — the fixed point your projects are measured from, made of every record it has ever absorbed. It pairs with HingePoint by design: two precision-instrument names, one deliberate family.