<Default> (Default Button)

This element specifies that the object is a default (OK) button . If this element is specified without a value, it is assumed to be true. This element is used for buttons.

example:
<x:ClientData  ><x:Default>True</x:Default>
</x:ClientData>

The possible values for this element are defined by the ST_TrueFalseBlank simple type (§6.4.3.3).

Parent Elements

<ClientData>6.4.2.12)