UCHAR: A single, unsigned byte.
ULONG: A single, unsigned long integer consisting of 32 bits. This data type can have a range from 0 to 4,294,967,395 (0xffffffff).
UncPath: The location of a file in a network of computers, as specified in Universal Naming Convention (UNC) syntax.
unicast: A delivery method used by media servers for providing content to connected clients in which each client receives a discrete stream that no other client has access to.
Unicode: A character encoding standard developed by the Unicode Consortium that represents almost all of the written languages of the world. The Unicode standard provides three forms (UTF-8, UTF-16, and UTF-32) and five schemes (UTF-8, UTF-16, UTF-16 BE, UTF-32 LE, and UTF-32 BE). Unless otherwise specified, all Unicode strings in Windows protocols follow the UTF-16 form with no Byte Order Mark (BOM).
Unicode string: A Unicode 8-bit string is an ordered sequence of 8-bit units, a Unicode 16-bit string is an ordered sequence of 16-bit code units, and a Unicode 32-bit string is an ordered sequence of 32-bit code units. In some cases, it may be acceptable not to terminate with a NULL character.
Uniform Resource Locator (URL): A string of characters in a standardized format that identifies a document or resource on the World Wide Web.
unique identifier (UID): A pair consisting of a GUID and a version sequence number to identify each resource uniquely. The UID is used to track the object for its entire lifetime through any number of times that the object is modified or renamed.
Universal Disk Format (UDF): A type of file system for storing files on optical media.
universal group: A group that can appear in access control lists (ACLs) anywhere in the forest, and can contain other universal groups, global groups, and users from anywhere within the forest.
Universal Naming Convention (UNC): A standard naming format for specifying the location of network resources such as shared files or devices on a network. The format is "\\<servername>\<share>\<filename>", where <servername> is a NetBIOS name, FQDN domain name, or IPv4 address; <share> is a logical share point for accessing <servername>; and <filename> is the name of the file or device.
Universal Plug and Play (UPnP): A set of computer network protocols, published by the UPnP Forum [UPnP], that allow devices to connect seamlessly and that simplify the implementation of networks in home (data sharing, communications, and entertainment) and corporate environments. UPnP achieves this by defining and publishing UPnP device control protocols built upon open, Internet-based communication standards.
universal serial bus (USB): An external bus that supports Plug and Play installation. It allows devices to be connected and disconnected without shutting down or restarting the computer.
universally unique identifier (UUID): A 128-bit value. UUIDs can be used for multiple purposes, from tagging objects with an extremely short lifetime, to reliably identifying very persistent objects in cross-process communication such as client and server interfaces, manager entry-point vectors, and RPC objects. UUIDs are highly likely to be unique. UUIDs are also known as globally unique identifiers (GUIDs) and these terms are used interchangeably in the Microsoft protocol technical documents (TDs). Interchanging the usage of these terms does not imply or require a specific algorithm or mechanism to generate the UUID. Specifically, the use of this term does not imply or require that the algorithms specified in [RFC4122] or [C706] must be used for generating the UUID.
unmarshal: (1) The process of deserializing one or more data structures from an octet stream using a specific transfer syntax (for example, unmarshaling a 32-bit integer).
unmasked disk: A disk that is visible to the local machine.
unnamed stream: See Main Stream.
unplug a channel: To switch a channel from plugged channel mode to unplugged channel mode.
unplugged channel mode: A channel mode in which an IN channel or OUT channel instance sends protocol data units (PDUs) immediately instead of queuing them. This is the default mode for channels.
update: An add, modify, or delete of one or more objects or attribute values.
UPDATE: The set of metadata pertaining to a file or file deletion. The main fields in an update consist of the unique identifier (UID), global version sequence number (GVSN), file name, file attributes, and flags indicating whether the update is for an existing file, or for a file deletion.
update sequence number (USN): (1) A monotonically increasing sequence number used in assigning a stamp to an originating update. For more information, see [MS-ADTS].
(2) The offset from the beginning of the change journal stream that uniquely identifies a change journal record.
(3) Contains a 64-bit value representing the number of 100-nanosecond intervals since January 1, 1601 Coordinated Universal Time (UTC). This is updated whenever the packageRegistration object is modified on the server to match the server's UTC time at the time of the update.
updates: A set of UPDATE entities.
upgrade: A relationship between software packages in which the upgrading application will replace a particular software installation package (the upgraded application) if it exists on a client and was installed through the software installation protocol extension. Logically, this means that the client application will be uninstalled and the upgrading application will be installed.
upgrading application: If two applications are related due to an upgrade, this is the application to remove from the client when the upgrading application is installed.
uplevel trust: A trust in which both peers are running Windows 2000 or later domain controllers.
upstream partner: The partner that sends out change orders, files, and folders.
URI: This term is used as specified in [RFC2616].
URL: See Uniform Resource Locator (URL).
User Account Control (UAC): A set of security options associated with a security principal. Particular options designate the role computers in the domain.
user account database: A database that maintains user account information.
user account database replication: A mechanism for synchronizing the user accounts database among multiple domain controllers.
user account information: The user name, password, and groups in which the user account has membership.
user agent: An HTTP user agent, as specified in [RFC2616].
user assistance resource: A UnicodeString containing a URL pointing to information that may be helpful to users of the application when viewing information about the application through a software maintenance tool. This is defined by the administrator who deploys the application.
user connection: A connection to a printer (shared from a print server) on a client machine. A connection is displayed in the user interface as a printer. User connections are displayed for only one user of a particular client machine.
User Datagram Protocol (UDP): The connectionless protocol within TCP/IP that corresponds to the transport layer in the ISO/OSI reference model.
user-defined message tag (MTAG): A message that is sent within the context of an established connection. See also Message Tag (MTAG).
user message: A message sent between instances of an application using the DirectPlay network library as a transport.
user policy mode: A mode of policy application used to retrieve settings for an authenticated domain user account, interactively logged on to a client.
user principal name (UPN): A user account name (sometimes referred to as the user logon name) and a domain name identifying the domain in which the user account is located. This is the standard usage for logging on to a Windows domain. The format is: firstname.lastname@example.org (in the form of an e-mail address). In the Active Directory directory service, the UPN is the userPrincipalName attribute of the account object, as specified in [MS-ADTS].
user profile: A collection of attributes on a user object that are used to customize an end-user experience.
user profile folder: A storage location in an operating system that provides the operating system and applications with a per-user location with conventional semantics. For example, each user on a Windows operating system has his or her own documents, music, videos, and pictures user-profile folders in which he or she may store per-user data.
user-scoped Group Policy object path: A scoped Group Policy object (GPO) path that ends in "\User."
USHORT: A single, unsigned short integer consisting of 16 bits. This data type can have a range from 0 to 65,535 (0xffff).
USN: See update sequence number (USN).
UTC (Coordinated Universal Time): A high-precision atomic time standard that approximately tracks Universal Time (UT). It is the basis for legal, civil time all over the Earth. Time zones around the world are expressed as positive and negative offsets from UTC. In this role, it is also referred to as Zulu time (Z) and Greenwich Mean Time (GMT). In these specifications, all references to UTC refer to the time at UTC–0 (or GMT).
UTF-16: A standard for encoding Unicode characters, defined in the Unicode standard, in which the most commonly used characters are defined as double-byte characters.
UTF-16LE (Unicode Transformation Format, 16-bits, little-endian): The encoding scheme specified in [UTF16] for encoding Unicode (see [Unicode30]) characters as a sequence of 16-bit codes, each encoded as two 8-bit bytes with least-significant-byte first.
UTF-8: A byte-oriented standard for encoding Unicode characters, defined in the Unicode standard.
UUID: See universally unique identifier (UUID).
UUID or GUID: See universally unique identifier (UUID). See globally unique identifier (GUID).