Date validation of different formats in RPG

All,

 Does anyone have any experience or 'best practices' for validating dates of
differing formats in RPG?

 Scenario: we receive data from various sources, each one of which seems to
have a different idea of how dates should be formatted. Here in the US most
data entry operators use *MDY format, but others feel free to use *MDY0,
*USA, etc, etc. Demanding consistency won't work - these are our customers
and part of the 'value' our company offers is to allow them to send data in
the format they feel comfortable with.

 At the time they need to validated, the dates have already been parsed into
10A fields in a subfile program, I'm considering writing a procedure to make
a 'best-guess' as to the date's format - something akin to the code below.
Someone has to have addressed this situation before - would you care to give
out a few pointers?

Thanks,
JK

C                   If        s_DatP <> *blank                      
C     *MDY          Test(de)                s_DatP                  
C                   If        not %error                            
C     *MDY          Move      s_DatP        w_Date                  
C                   Else                                            
C     *MDY0         Test(de)                s_DatP                  
C                   If        not %error                            
C     *MDY0         Move      s_DatP        w_Date                  
C                   Else                                            
C     *USA          Test(de)                s_DatP                  
C                   If        not %error                            
C     *USA          Move      s_DatP        w_Date                  
C                   Else                                            
C     *USA0         Test(de)                s_DatP                  
C                   If        not %error                            
C     *USA0         Move      s_DatP        w_Date                  
C                   Else                                            
C                   Eval      SflValErrF = 'Y'                   
C                   CallP     SndMsgToThisPgmQ( 'USR0406' )         
C                   Seton                                        75 
C                   EndIf
C                   EndIf   
C                   EndIf   
C                   EndIf   
C                   EndIf