this invention relates generally to mobile carpentry and drafting devices and , more particularly , to an integral combination type device which is capable of performing multiple geometry measuring functions within a single instrument . the invention relates specifically to a unique combination of independent carpentry functions into a single device to replace separate tools heretofore required to perform individual functions . the squareangle may be used to check surfaces for plumb and levelness ; check inside and outside squareness ; find the center of a circle , square , or octagon ; mark 45 ° and right angles ; scribe lines ; measure distance ; and perform other geometry and drafting functions without the aid of additional devices .