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CWR file validation
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File level validation
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ID     Constraint                                      Failure level
=====  ==============================================  =============
1      File should be readable                         ER
2      First record should be HDR                      ER
3      Second record should be GRH                     ER
4      Groups open with GRH and close with GRT         ER
5      Last record is TRL                              ER
6      GRH should be followed by a Transaction header  ER
7      GRT should be followed by a GRH or TRL          ER
7      Only a single HDR and a single TRL exist        ER
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