GBT1184-1996标准（英文版）

cylindricitytoleranceforsimplifying.A9ParallelismStraightnesstolerance;DimensiontoleranceThegeometricaltoleranceadoptstolerancezone,sotheparallelismerrorcanbecontrolledbydimensiontolerance(seeFigureA3);ifthefeaturearemaximummaterialdimensionsanypoint,itiscontrolledbystraightnessandplaneness(seeFigureA4).Parallelismerror≤dimensionaltoleranceParallelismerror≤straightnesstoleranceFigureA3ExampleofParallelismFigureA4ExampleofParallelismUnnotedToleranceUnnotedToleranceA.10SymmetryTakethelongeroneasreferenceforsymmetry;iftwoofthemarethesamelengthtakeanyoneasreference.SeeFigureA5oftheexample.a)Reference:thelongerfeature(l2);b)Reference:thelongerfeature(l2);c)Reference:thelongerfeature(l2);d)Reference:thelongerfeature(l2);FigureA5ExampleofSymmetryA.prehensiveexampleandexplanationpleaseseeFigureA6.