Datum reference is a concept used in carpentry, metalworking, needlework, Geometric dimensioning and tolerancing (GD&T) and similar activities.
In carpentry, an alternative, more common name is "face side" and "face edge". The artisan nominates two straight edges on a workpiece as the "datum edges", and they are marked accordingly. One convention is to mark the first datum edge with a single slanted line (/) and the second with double lines (//). For most work, the datum references of the workpiece need to be square. If necessary they may be cut, planed or filed to make them so. In subsequent marking out, all measurements are then taken from either of the two datum references.
Read more about Datum Reference: Engineering
Famous quotes containing the words datum and/or reference:
“Language fails not because thought fails, but because no verbal symbols can do justice to the fullness and richness of thought. If we are to continue talking about “data” in any other sense than as reflective distinctions, the original datum is always such a qualitative whole.”
—John Dewey (1859–1952)
“In writing these Tales ... at long intervals, I have kept the book-unity always in mind ... with reference to its effect as part of a whole.”
—Edgar Allan Poe (1809–1849)