| iNTERFACEWARE Products Manual > Installing and Using Chameleon > Learning the Advanced Features > Auto ACKnowledgments > Creating a VMD File to Send Acknowledgment Messages > How are Auto ACKnowledgments Possible? | 
    
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 This hl7.vmd file is set up to generate auto ACKnowledgments (in this case, a positive acknowledgment using the AA code). In the VMD file you will notice that a default and an ACK message definition has been set up. These messages are defined in the Options window using the Special Messages tab, as shown below:  
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