use-when 

A condition for the action of the activity Element. The action will just be executed, if the condition returns true.

value
XPath expression. It expects as return value an xs:boolean.

Attribute Information

Used By

Attribute Group sqf:activityBase

Source 

<xs:attribute name="use-when" use="optional" type="xs:string" default="true()">
  <xs:annotation>
    <xs:documentation>A condition for the action of the activity Element. The action will just be executed, if the condition returns true.</xs:documentation>
    <xs:documentation source="value">XPath expression. It expects as return value an xs:boolean.</xs:documentation>
  </xs:annotation>
</xs:attribute>

Sample