Means:
(a) where the person carrying out the check has not previously done so in relation to a particular certificate, to successfully confirm the certificate path validation by using:
(i) the path validation algorithm specified in IETF RFC 5280; or
(ii) where the algorithm identified in IETF RFC 5280 is not appropriate for the certificate for which validity is being confirmed, such other certificate path validation as is appropriate in relation to that type of certificate; or
(b) where the person carrying out the check has previously carried out the check in paragraph (a) in relation to a particular certificate, that the certificate has not subsequently been revoked, and its validity period has not expired.