This is the date that the Major Diagnostic Categories became effective for this diagnosis. This is normally the beginning of a fiscal year.
1)= S ^ICD9(DA(1),4,"B",$E(X,1,30),DA)=""
2)= K ^ICD9(DA(1),4,"B",$E(X,1,30),DA)
^ICD9(IEN1,4,"B",EFF,IEN2) - Where IEN1 is the internal entry number in the ICD Diagnosis file #80, EFF is the effective date for the Major Diagnostic Category and IEN2 is the internal entry number in the MAJOR
DIAGNOSTIC CATEGORY multiple where the MDC is stored.