# TOLERANCE Dialog box [GstarCAD 2021](Help%20System/GSTARCAD/2021/Index.md) → [Commands](Help%20System/GSTARCAD/2021/Commands/(Commands).md) → [03 Dialog Boxes](Help%20System/GSTARCAD/2021/Commands/03%20Dialog%20Boxes/(Dialog%20Boxes).md) The TOLERANCE dialog box is used to specify the symbols and values for a feature control frame.  ## Function Description: After selecting geometry features symbols, the Geometric Dialog box closes and prompts to specify the location to place the feature control frame. Relative Glossary: **Symbol:** Select a geometric characteristic symbol from "Symbol" dialog box.  **Tolerance 1:** Create the first tolerance value in the feature control frame. The tolerance value means the amount by which the geometric features can deviate from a perfect shape. Users can insert a diameter symbol. > **The first box:** > Click the first box to insert a symbol. For example, insert a diameter symbol. > >  > **The second box:** > Create a tolerance value. Input a tolerance value to the second box. > >  > **The third box:** > Display the "Material Condition" box, from which users could select a modifying?symbol. Those symbols act as modifiers to the geometric characteristic and the tolerance value of features that can vary in size. >  > >  **Tolerance 2:** Create the second tolerance value in the feature control box. Specify the second tolerance value in the same way as the first one. **Datum 1:** Create the primary datum reference value. The datum reference is composed by a value and a modifying symobl. In theory, the datum is an accurate geometric reference, which is a tolerance zone used to create features. > **The first frame:** > Create a datum reference value. > >  > **The second frame:** > Display the "Material Condition" box, from which users could select a modifying?symbol. These symbols act as modifiers to the datum reference. >  **Datum 2:** Create the secondary datum reference in the feature control box, which is in the same way as the primary datum reference.  **Datum 3:** Create the tertiary datum reference in the feature control box, which is in the same way as the primary datum reference.  **Height:** Create a projected tolerance zone value in the feature control frame. A projected tolerance zone controls the height variation of the extended portion in the fixed perpendicular part, as well the location tolerance controls the tolerance accurancy.  **Projected Tolerance Zone:** Insert a projected tolerance zone symbol after the projected tolerance zone value.  **Datum Identifier:** Create a datum-identifying symbol consisting of a reference letter. A datum is a theoretically exact geometric reference from which you can establish the location and tolerance zones of other features. A point, line, plane, cylinder, or other geometry can serve as a datum.  ## Other versions with matching text [GstarCAD 2016](../../../2016/Commands/03%20Dialog%20Boxes/TOLERANCE%20Dialog%20box.md) · [GstarCAD 2017](../../../2017/Commands/03%20Dialog%20Boxes/TOLERANCE%20Dialog%20box.md) · [GstarCAD 2018](Help%20System/GSTARCAD/2018/Commands/03%20Dialog%20Boxes/TOLERANCE%20Dialog%20box.md) · [GstarCAD 2019](Help%20System/GSTARCAD/2019/Commands/03%20Dialog%20Boxes/TOLERANCE%20Dialog%20box.md) · [GstarCAD 2020](Help%20System/GSTARCAD/2020/Commands/03%20Dialog%20Boxes/TOLERANCE%20Dialog%20box.md)