# Geometric Tolerance Dialog Box [GstarCAD 2027](Help%20System/GSTARCAD/2027/Index.md) → [Commands](Help%20System/GSTARCAD/2027/Commands/(Commands).md) → [Dialog Boxes](Help%20System/GSTARCAD/2027/Commands/03%20Dialog%20Boxes/(Dialog%20Boxes).md) ## Function Description: The Geometric Tolerance dialog box is used to specify the symbols and values for a feature control frame. After selecting geometry features symbols, the Geometric Tolerance dialog box closes and prompts to specify the location to place the feature control frame.  **Dialog Box Options:** ## **Symbol** Selects a geometric characteristic symbol from the Symbol dialog box.  ## **Tolerance 1** Creates 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 form. Users can insert a diameter symbol. - **The first box:** Clicks the first box to insert a symbol. For example, insert a diameter symbol. - **The second box:** Creates a tolerance value. Enter a tolerance value to the second box. - **The third box:** Displays the Material Condition dialog box, from which users can select a modifying symbol. These symbols act as modifiers to the geometric characteristic and the tolerance value of features that can vary in size.  ## **Tolerance 2** Creates the second tolerance value in the feature control frame. Specify the second tolerance value in the same way as the first one. ## **Datum 1** Creates the primary datum reference value in the feature control frame. The datum reference is composed by a value and a modifying symbol. In theory, the datum is an accurate geometric reference, which is a tolerance zone used to create features. - **The first frame:** Creates a datum reference value. - **The second frame:** Displays the Material Condition dialog box, from which users can select a modifying symbol. These symbols act as modifiers to the datum reference.  ## **Datum 2** Creates the secondary datum reference in the feature control frame, which is in the same way as the primary datum reference.  ## **Datum 3** Creates the tertiary datum reference in the feature control frame, which is in the same way as the primary datum reference.  ## **Height** Creates 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** Inserts a projected tolerance zone symbol after the projected tolerance zone value. ## **Datum Identifier** Creates 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. --- [Original help](https://www.gstarcad.net/help/GstarCAD_2027_en-US/detail/commandReferences/TOLERANCE_DIA.html) · © Gstarsoft Co., Ltd.