|InfoPath Developer Reference|
Version Added: InfoPath 2003
expression An expression that returns a Error object.
The detailed error message is the longer error message that users can choose to view when data validation fails in their forms.
Security Level 2: Can be accessed only by forms running in the same domain as the currently open form, or by forms that have been granted cross-domain permissions.
In the following example, the DetailedErrorMessage property of the Error object is used to display the detailed message of an error in a message box: