Production First Software Encyclopedia of Typography and Electronic Communication : X

X3 A color sensor technology produced on a CMOS chip by layering red-sensitive, green-sensitive and blue-sensitive substrates. This allows a larger number of pixels per surface area, and, therefore, higher resolution. The bad news is that there is crosstalk between sensor layers. This is usually corrected by software algorithms.

X-axis See Han unification model.

XBEL An acronym for XML Bookmark Exchange Language, a markup language designed specifically for coding browser bookmark data.

.XBM file See bitmap formats.

XDR XMLDataReduced. A proprietary dialect of XML Microsoft uses in products.

xenophile A person who is attracted to anything foreign (automobiles, clothes, languages, lifestyles, people, products, etc.).

xerography The name given to a process used in copiers and laser printers whereby a laser is used to write the image of a composed page or document on a light-sensitive drum, which becomes electrically charged. Powdered toner particles become charged and are then attracted to the drum, and are transferred and fused to a medium (paper or plastic sheeting). The process was invented by the Xerox Corporation.

x-height or x height The height of the lower case x, measured from the baseline, which is close to the average height of all lower case characters not including their ascenders.

XLF An acronym for eXtensible Log Format, a markup language for log messaging.

x-line or x line An imaginary line at the x-height running parallel with the baseline. Same as « mean line. »
x-height and x-line illustrations

XHTML An abbreviation for eXtensible HyperText Markup Language, an application of XML which uses a DTD to produce a reformulation of HTML in XML terms so that an XML structure can be used within a document otherwise looking like HTML.

The major lexical differences between HTML and XHTML are that:
1) All tag strings must be lowercase;
2) Every opening tag used in XHTML must be paired with a closing tag or have a string terminator within the tag; and
3) !CDATA constructs are allowable.
One of the most frequently used HTML tags which does not have to obey the requirement (2) in HTML is the paragraph marker <p> . The missing tag would be </p> . An example of a tag with a string terminator in it is <br /> . There are other HTML tags which must have string terminators besides <br /> .

Several depths of XHTML can be envoked by the DTD statement, including STRICT where XML patches can be used in the ordinary way and TRANSITIONAL where an XML namespace must be declared at the beginning of an XML coding patch. The TRANSITIONAL form is less restrictive on, and, therefore, more compatible with, ordinary HTML coding.

XHTML Basic A subset of XHTML intended for Internet appliances. It does not support such HTML and XHTML features such as frames, imagemaps, objects, and scripting.

XLink An application of XML which broadens the capabilities of hyperlinks.

xMCL An abbreviation for extensible Media Commerce Language, a markup language for the commercial implementation of the IPMP standard. The development of this markup language was announced in June 2001 by a group of media software developers and vendors, including Adobe Systems, IBM, InterTrust, MGM, RealNetworks, Sony, and Sun Microsystems. See also XrML.

XMI An abbreviation for eXtensible Markup Language Metadata Interchange. An interoperability (exchange) data file standard for resources. A typical use would be to share resources between tools. It was developed by IBM, Oracle Corp. and Unisys Corp.

XML An abbreviation for eXtensible Markup Language. A markup language which is a subset and dialect of SGML with respect to syntax, but more extensive than HTML. As a target goal, it was designed to be used on the World Wide Web and to be interoperable with HTML and SGML. XML includes approximately 80% of the functionality of SGML but with only a fraction of SGML's complexity. XML can work in conjunction with scripting languages. Whereas markup languages are designed to describe text, scripting languages are designed to process text.

Among new features, XML supports custom tag names, webcasting, as well as support for embedable and downloadable fonts. The native text character encoding for XML is ISO 10646 in UCS-2 and UTF-8 forms, thereby supporting Unicode. Microsoft's Channel Definition Format (for webcasting) is standardized on XML, as is Netscape's. XML is currently in draft status, with the W3C overseeing its development. XML is an example of vendor-neutral software technology.

XML-QL An abbreviation for eXtensible Markup Language-Query Language, an application of XML to extend capabilities of query, search, and translation of data.

XML schema language or XML schema An alternative to DTD's developed by the W3C. It is a language which defines the tags and structure of a document written in XML or XML-based markup languages. XML schema features are a superset of DTD features.

XrML An abbreviation for eXtensible rights Markup Language, a markup language for the commercial implementation of the IPMP standard. The development of this markup language was announced by Microsoft and ContentGuard. See also xMCL.

xSDL An abbreviation for external Digital Subscriber Line.

XSL An abbreviation for eXtensible Style Sheet Language. A new style sheet format supplanting, and going beyond, Cascading Style Sheets (CSS) used with HTML and XML.

XUL An abbreviation for XML-based User Interface Language. A Netscape utility which enables developers to customize the operating system-browser interface, so that a single kernel of browser code can work on all operating systems.

.XWD file See bitmap formats.

X/Window System A standardized graphical user interface for operating system controls, running under Unix.

X3D An abbreviation for eXtensible 3D file format for VMRL.

X.509 A standard for digital certificates.

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