This is a very important event to implement an Engine for the engine control. It is invoked when a parsing error occurs. You should implement some kind of acknowledgement message here, either an ACK or a NACK, that can be passed back in the ResultMessage String. Below you will find an example of this implementation:

Private Sub Engine_OnParseError(Code As Long, Description As String, 
 MessageData As String, TreeView As String, ResultMessage As String)
   DisplayOutput Description
   ' Send back a hardcoded NACK.
   ResultMessage = "MSH|^~\&|||||||NACK|||||||||" & CR & "MSA||||||" & CR
End Sub

The parameters passed to the OnParseError event are as follows:

• Code - Error code of the error.
• Description - A full description of the parsing error. This report is very useful and contains a lot of diagnostic information.
• MessageData - The message that caused the error.
• TreeView - A textual tree view of the message with errors.
• ResultMessage - The variable used to return a string to the Parse function.