“Dimensions” Tab 

Linear Dimensions. This group contains the following parameters:
Minimum digits. Sometimes, a certain number of decimal digits are required to be displayed on a dimension, including trailing zeros. This can be insured with the “Minimum digits” setting. For example, setting the value “3”, then the dimension value 28.5 will be shown on the drawing as 28.500.
Accuracy. Defines rounding accuracy of the linear dimension values. For example, the accuracy "0.01" means the dimension values will be rounded to the second decimal digit. The "0" accuracy means the dimension values will not be rounded.
Units. Defines the linear dimension value representation. This is mostly relevant to dimension values in inches.
Scale:
Scale factor. Reflects the scale factor of dimension value conversion per the dimension scale parameter. All dimension values will be multiplied by this scale factor. If “Dimension scale” is “Custom”, one can enter your own scale factor for converting dimension values of linear dimensions.
Scale. Defines the way of converting dimension values of the linear dimensions. The following conversion systems can be selected from the list:
No. No dimension conversion is done.
Inch/Metric. In this case, conversion of the dimension values will be done per the parameter “Units” on the “General” tab. If the inches system is set, then the linear dimension values will be converted to millimeters, that is, multiplied by the scale factor of 25.4. If the metric system is set, then the dimension values will be converted into inches, that is, multiplied by the scale factor of 1/25.4.
Thus, one can work with a drawing in metric system while applying dimensions with values in inches, and vise versa.
Custom. With this setting, an arbitrary dimension value conversion factor can be specified.
Apply scale to projections. This parameter is used in the 3D version of the system only. It has an effect on dimension creation within 2D projections in the case when a dimension scale is defined in the command “ST: Set Document Parameters for the 2D page that contains the projection. When the flag is set, then the specified scale is applied to the dimensions on a 2D projection with a scale; if the flag is cleared, the scale is ignored.
Dimensions:
Standard. Defines the appearance of dimensions on a drawing. A dimension standard can be selected from the list. Three standards are provided in the list – ANSI, BS308 and DIN/ISO.
BS308 stands for ANSI standard for architects or British standard. Upon changing the dimension standard, the dimensions automatically redraw to comply with the new standard.
Alignment spacing. Specifies spacing when aligning dimensions with offset.
Tolerance grade. Defines the tolerance grade for dimensions on a drawing. If the accuracy parameter of the dimension is set equal to this parameter then the tolerance string and limits will not be displayed as part of the dimension.
Angular Dimensions. This group contains the following parameters:
Units. Defines the angular dimension value representation.
Minimum digits. Defines the minimum number of decimal digits for angular dimensions.
Accuracy. Defines rounding accuracy of the angular dimension values.
Spacing in tolerance text. When this option is enabled, tolerances of dimensions are separated with spaces for easy reading.
Alternative scale. Defines the way of converting dimension values of the alternative dimensions. The following conversion systems can be selected from the list:
No. No alternative dimension conversion is done.
Inch/Metric. In this case, conversion of the dimension values will be done per the parameter “Units” on the “General” tab. If the inches system is set, then the alternative dimension values will be converted to millimeters, that is, multiplied by the scale factor of 25.4. If the metric system is set, then the alternative dimension values will be converted into inches, that is, multiplied by the scale factor of 1/25.4. This allows setting both metric and inches value using dual dimensions.
Custom. With this setting, an arbitrary scale factor can be specified for converting an alternative dimension value.
Scale factor. Reflects the scale factor for converting alternative dimension values per the alternative scale parameter.