The description reads:
Each CA Certificate may have a revocation list. This check fails if this list is not available (i.e. a network interruption prevents the engineering tool from accessing the list). No error is reported if the Administrator disables revocation checks for a CA Certificate.

The revocation list must also be checked.
Furthermore, the integrity/authenticity of the CRL must be checked, i.e. the digital signature of the CRL. This included the certificate path validation as well.