[A] major subdivision of an assembly consisting of a package of parts, elements, and circuits that perform a specific function. [INFOSEC-99]

A carrier used to modulate another carrier.
Note: The modulated carrier can be used to modulate another carrier, and so on, so that there can be several levels of subcarriers, i.e., several intermediate carriers.

A class derived from another class by specialization. [T1.260-1998]

1. In cryptography, an entity whose public key is certified in a public key certificate.
2. Generally, a person, process, or device, causing information to flow among objects or change to the system state. [INFOSEC-99]
3. An active entity, generally in the form of a person, process, executing program or device that causes information to flow among objects or changes… (Read More →)

An authority recognized in a Security Domain as a trusted source of security information concerning security subjects (human beings and Applications) [ECMA138].

Sensitivity label(s) of the objects to which the subject has both read and write access. Security level of a subject must always be dominated by the clearance level of the user associated with the subject. [INFOSEC-99]

1. In a layered open communications system, a specified subset of the services, functions, and protocols included in a given layer.
2. In the Open Systems Interconnection--Reference Model, a subdivision of a given layer, e.g., a conceptually complete group of the services, functions, and protocols included in the given layer.

In an Internet Protocol (IP) address, an extension that allows users in a network to use a single IP network address for multiple physical subnetworks.
Note: The IP address contains three parts: the network, the subnet, and host addresses. Inside the subnetwork, gateways and hosts divide the local portion of the IP address into a subnet address and a host… (Read More →)

A number that is used to identify a subnetwork so that IP addresses can be shared on a local area network.

1. A collection of equipment and physical transmission media that forms an autonomous whole and that can be used to interconnect systems for purposes of communication.
2. Specifically, a collection of open system interconnection (OSI) end systems and intermediate systems under the control of a single administrative domain and using a single network access protocol.
Note: Examples of subnetworks are… (Read More →)