VeriFone MX800 series Programmer's Manual page 221

In case of an input error, the packet looks like:
STX
packet type
error code
error ETX
1H Start of text, value 02h
2AN value '73'
1N "1" = No key
"2" = key serial number error
"3" = PIN length over Max
"4" = PIN length under Min
"6" = Over 1 million transactions
1H End of text, value 03h
IPP L
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ipp_read()
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