|InfoPath Developer Reference|
Version Added: InfoPath 2003
expression An expression that returns a Error object.
The ConditionName property is used only for custom errors; it is not used for schema validation–generated or system-generated errors. If the type of error is schema validation generated or system generated, the ConditionName property will return null.
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 ConditionName property of the Error object is used to display the name of a custom error in a message box: