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A fixed point all measurements refer to.
Also known as: Temporary benchmark archaeology, Survey datum marking
The archaeological survey mark from which all heights and positions on a site are measured.
Fixes the point from which all heights and positions on an archaeological site are measured.
Contexts: Technical drawing, Maps
Appears on every drawing of the site, so the datum is what lets separate plans made months apart be laid over each other.
Contexts: Technical drawing, Maps
A small triangle or cross with a dot at its centre, fixed at a point on the site and drawn on every plan.