A child of both the element <process> and the element <dmNode>, the element <variablePreSet> assigns a value to a local variable or global property before its parent element is traversed. The element <variablePreSet> contains the element <assertion>. An assertion contains the element <variableRef> or <globalPropertyRef> and the element <expression>. The element <variableRef> and the element <globalPropertyRef> have attributes which uniquely define a local variable or global property. The element <variableRef> has the attribute variableName. The element <globalPropertyRef> has attributes applicPropertyIdent and applicPropertyType. When an element <variablePreSet> is encountered in the data, the logic engine evaluates the expression and assigns the resulting value to the local variable or global property identified by the element <variableRef> or the element <globalPropertyRef>. One use case is that the element <variablePreSet> is used on an element <dmNode> with an external application call in order to assign values to one or more of the parameter variables to be passed to the application. On the element <process>, it can be necessary to preset to "noValue" the value of a global property representing wind speed prior to beginning a procedure because the wind speed can have changed since the value of that property was last accessed.