Property data formats control how units display in schedule tables, schedule tags, the Edit Property Set Data worksheet, and on the Properties palette. Units behave differently with real numbers in manual properties than they do with automatic properties.
Units for automatic properties are collected directly from the objects. An automatic property, such as width, uses the units specified on the Units tab in the Drawing Setup dialog box by default. Using different property data formats allows you to override the default format.
When you use a property data format, the AutoCAD units are converted to display as defined in the property data format. You can specify a property data format on the Definition tab of a property set definition.
Units specified for manual properties in the property set definition control what is stored in the drawing. The Extended Data tab of the Properties palette displays the units as defined in the property data format. When the type of unit is Real, you can select a format and type of unit in the property set definition to override the property data format when entering units.