Geometric dimensioning and tolerancing (GD&T) is a system for defining and communicating engineering tolerances. It uses a symbolic language on engineering drawings and computer-generated three-dimensional solid models that explicitly describe nominal geometry and its allowable variation. This highly specialized symbol font is designed specifically to be used by engineers to describe CAD produced outside the CAD environment. Included is a chart featuring character names and keyboard placement. Complies with ASME Y14.5M-1994. Updated to include 2009 addition of ‘unilateral’ symbol.