The security and privacy controls implemented in lieu of the controls in the baselines described in NIST Special Publication 800-53 that provide equivalent or comparable protection for a system or organization.
Sources:
NIST SP 800-37 Rev. 2
The security and privacy controls employed in lieu of the controls in the baselines described in NIST Special Publication 800-53B that provide equivalent or comparable protection for a system or organization.
Sources:
NIST SP 800-53 Rev. 5
NIST SP 800-53A Rev. 5
from
NIST SP 800-53B
NIST SP 800-53B