Which Verification Flag should be set when calling CertificateChain.VerifyChain so that expired remote certificates are ignored?

I guess it is one of these, but the documentation isn't very explicit:
-IgnoreTimeNotValid
-IgnoreCtlTimeNotValid
-IgnoreTimeNotNested
-IgnoreAllTimeChecks (I guess this one works, but it seems too general)

(by the way, this library is awesome. Good job!)

Actually, I meant more of something like this: Which flag should be set so that expired remote certificates are considered as Valid?