GD&T Flatness is a common symbol that references how flat a surface is regardless of any other datum’s or features. It comes in useful if a feature is to be defined on a drawing that needs to be uniformly flat without tightening any other dimensions on the drawing.

The flatness symbol defines how imperfect it can be. The wavy surface must fall between two parallel planes where the distance between them is defined in the flatness GD&T callout. GD&T Symbol: ⏥ (Unicode: U+23E5)

The first block contains the geometric characteristic symbol for flatness. It is represented by a parallelogram. Since the tolerance zone for flatness is a total wide zone, there is no need for a symbol in the second block for the tolerance type as this is the default zone.

Drafting Symbols Symbols provide a “common language” for drafters all over the world. However, symbols can be meaningful only if they are created according to the relevant standards or conventions. This document describes and illustrates common dimensioning, GD&T, architectural, piping, and electrical symbols. Standard Dimensioning Symbols