Defines a custom validation (or error condition) for a specific XML Document Object Model (DOM) node in a form's underlying XML document.
xsd:complexType| Name | Description | 
|---|---|
| expression | (Required attribute) An XPath expression (relative to the expressionContext attribute, if specified) that must be evaluated to validate the XML DOM node specified in the match attribute. | 
| expressionContext | (Optional attribute) Specifies the XML DOM node on which the expression specified in the expression attribute is rooted. | 
| match | (Required attribute) Identifies the XML DOM nodes on which the custom validation is declared. | 
| showErrorOn | (Optional attribute) Identifies XML DOM nodes (within the context of the expression context XML DOM node) on which the error should be displayed when the form is filled out. | 
| errorMessage | (Required element) Specifies the error message to be returned if the value of the specified XML DOM node is considered to be invalid. | 
The errorCondition element is an optional element of the customValidation element.
The following is an example of the errorCondition element:
<xsf:customValidation>
   <xsf:errorCondition
      match="/exp:expenseReport"
      expressionContext="exp:reportDate"
      expression="msxsl:string-compare(., ../exp:startDate) < 0 and ../exp:startDate != """
      showErrorOn=".">
      <xsf:errorMessage
         type="modeless"
         shortMessage="The report date occurs before the end of the expense period.">
         The report date occurs before the end of the expense period. Verify that this is correct.
      </xsf:errorMessage> 
   </xsf:errorCondition>
</xsf:customValidation>