QlikView uses an XML file to define extension properties. The Definition.xml file is mandatory, and defines properties of the extensions, like how many Dimensions and Measures are used. It can also be used to initialize properties in the extension and to generate a user interface for setting up the extension.
Syntax for the Definition.xml file is as follows:

<ExtensionObject Path="" [Type="object|document"] [Label=""] [Description=""] [PropertiesPage=""] [PageWidth=""] [PageHeight=""]> Type is a new attribute for version 11, type=object is the default.
Default PageHeight is 40, default PageWidth is 20. Increase if you want more data.
<Dimension [Label=""] [Require="" | Prefer=""] [TargetName=""] [Initial=""] [OtherCounted=""] [Multiple=""] /> Label is for the automatic property page generation.
Initial means that QlikView will initialize the Dimension.
TargetName is used for drag and drop support.
OtherCounted defines how many distinct values you want. If you set it to 5 you will get the 4 most frequent values + an 'Other' category.
Use the attribute Multiple if you want a dynamic number of Dimensions.
<Measurement [Label=""] [Width=""] [TargetName=""] [Initial=""] [Multiple=""] /> Width is for the property page generator.
The other attributes works as for Dimension tag.
<Text [Label=""] [Type="text,checkbox,select,color"] [Select=""] [SelectLabel=""] [Width=""] [Expression=""] /> Use for your own clientside properties.
Type text is the default and will simply create a inputfield.
Type checkbox will create a checkbox and color will use the standard QlikView colorpicker.
Select will create a HTML select. Values for the select should be in Select attribute, comma separated and labels in SelectLabel.
<Property [Name=""] [Value=""] [Type="String|Bool"] /> Use it to define properties that should be available server-side, with the GetExtendedProperty() call.
<Initiate [Name=""] [Value=""] /> Use to initialize properties. Can be used for standard QlikView properties, like Caption etc, Dimensions and Measurements and user-defined properties.
<PropertiesPage [Version="11"] [File=""] /> Use it to have a special properties.qvpp for version 11.