FISMA & NIST RMF
Control Family
A logical grouping of related security or privacy controls within NIST SP 800-53. Revision 5 organizes its 1,007 controls into 20 families including Access Control (AC), Audit and Accountability (AU), Configuration Management (CM), Incident Response (IR), and Supply Chain Risk Management (SR). Each control identifier carries the family prefix, so AC-2 is the second control in the Access Control family.