(n.) A widely used standard for defining digital certificates. X.509 (Version 1) was first issued in 1988 as a part of the ITU X.500 Directory Services standard. When X.509 was revised in 1993, two more fields were added resulting in the Version 2 format. These two additional fields support directory access control. X.509 Version 3 defines the format for certificate extensions used to store additional information regarding the certificate holder and to define certificate usage. Collectively, the term X.509 refers to the latest published version, unless the version number is stated.
X.509 is published as ITU recommendation ITU-T X.509 (formerly CCITT X.509) and ISO/IEC/ITU 9594-8 which defines a standard certificate format for public key certificates and certification validation. With minor differences in dates and titles, these publications provide identical text in the defining of public-key and attribute certificates.
A windowing and graphics system developed at the Massachusetts Institute of Technology (MIT). MIT has placed the X-Window source code in the public domain, making it a particularly attractive system for UNIX vendors. Almost all UNIX graphical interfaces, including Motif and OpenLook, are based on X-Window.
Xanga (ZANG-uh) is an Internet Web host that provides its users (community) with access to their own online diaries and journals (often called blogs). A person who belongs to the Xanga community is called a “Xangan”. If someone has a Web blog on Xanga, they are being referred to as “having a Xanga.” Xanga services […]
A deductive rule-based query language currently under development by the I4 working group. Xcerpt is for querying XML, RDF and similar data formats. Xcerpt is well-suited for Semantic Web applications and is designed largely for software developers and researchers.
Xen is a virtual machine monitor (VMM) for x86-compatible computers. Xen can securely execute multiple virtual machines, each running its own OS, on a single physical system with close-to-native performance. Xen is open source, and is released under terms of the GNU General Public License.
A version of UNIX that runs on PCs. Xenix was developed by Microsoft Corporation and is compatible with AT&T’s System V definition.