and "h" (shaft) denote the zero line, where the lower (for holes) or upper (for shafts) limit deviation is zero.
This part provides tabulated numerical data for limit deviations based on the nominal size of the part (up to 3,150 mm). Key Components of the ISO 286 System
ISO 286-1:2010(en), Geometrical product specifications (GPS) iso 286 pdf
(A–ZC) are used for internal features ( holes ).
Standing for International Tolerance , these grades (from IT01 to IT18 ) define the magnitude or "width" of the tolerance zone. Lower numbers indicate higher precision. Common Types of Mechanical Fits and "h" (shaft) denote the zero line, where
This part defines the basic terminology, symbols, and principles of the system, including the concepts of clearance, interference, and transition fits.
Indicates the position of the tolerance zone relative to the nominal (basic) size. Standing for International Tolerance , these grades (from
The ISO 286 system uses an alphanumeric code to define a (e.g., H7 or g6 ).