From the FIG:
V664
Credit Score
Action Taken; Credit Score of Co-Applicant or Co-Borrower: Co-Applicant or Co-Borrower, Name and Version of Credit Scoring Model; Co-Applicant or Co-Borrower, Name and Version of Credit Scoring Model: Conditional Free Form Text Field for Code 8
An invalid Credit Score data field was reported. Please review the information below and update your file accordingly. 1) If Action Taken equals 4, 5, or 6, then Credit Score of Co-Applicant or Co-Borrower must equal 8888; and Co-Applicant or Co-Borrower, Name and Version of Credit Scoring Model must equal 9; and Co-Applicant or Co-Borrower, Name and Version of Credit Scoring Model: Conditional Free Form Text Field for Code 8 must be left blank