Property

Introduction
A property is a piece of information like a number or a text string that is attached to a FreeCAD document or an object in a document. Public properties can be viewed and modified in the Property editor.

Properties play a very important role in FreeCAD. As objects in FreeCAD are "parametric", this means that their behavior is defined by their properties, and how these properties are used as input for their class methods. See also PropertyLink:_InList_and_OutList

All property types
Custom scripted objects can use any of the property types defined in the base system:

Internally, the property name is prefixed with :

Remember that these are property. A single object may have many properties of the same type, but with different names.

For example:

This indicates an object with three properties of type "Float", named "Length", "Width", and "Height", respectively.

Scripting
FreeCAD scripting basics

A scripted object is created first, and then properties are assigned.

In general, properties are assigned by using the object's  method. On the other hand, properties are normally provided automatically by the parent object from which the scripted object is derived.

For example:
 * Deriving from provides only 4  properties: "Display Mode", "On Top When Selected", "Show In Tree", and "Visibility".
 * Deriving from provides 17  properties: the previous four, plus "Angular Deflection", "Bounding Box", "Deviation", "Draw Style", "Lighting", "Line Color", "Line Width", "Point Color", "Point Size", "Selectable", "Selection Style", "Shape Color", and "Transparency".

Nevertheless, properties can also be assigned using the view provider object's  method.

Source code
In the source code, properties are located in various files.

They are imported and initialized in.