Access control, the same principle applied outside of television.
Centers for Disease Control and Prevention | Transmission Control Protocol | Public-access television | Centers for Disease Control | Access Hollywood | air traffic control | Access Industries | gun control | Controlled-access highway | Media Control Charts | Internet Message Access Protocol | NFL Total Access | Lightweight Directory Access Protocol | Control Data Corporation | Board of Control for Cricket in India | The Olivia Tremor Control | Public, educational, and government access | open access | Microsoft Access | Christopher C. Kraft Jr. Mission Control Center | British Boxing Board of Control | Access | Gun Control Act of 1968 | Control Machete | biological pest control | Airborne early warning and control | Time division multiple access | Space-division multiple access | Random-access memory | Network traffic control |
The most prominent general deployments of SPKI/SDSI are E-speak, a middleware product from HP that used SPKI/SDSI for access control of web methods, and UPnP Security, that uses an XML dialect of SPKI/SDSI for access control of web methods, delegation of rights among network participants, etc.