A Complete Guide to Web Design

Glossary 529

Glossary

Web Design in a Nutshell, eMatter Edition

CSS-P

CSS with positioning. Refers to a proposal for adding positioning capabilities

with style sheets. The CSS-P proposal has since been rolled into the CSS2

Specification.

data fork
The portion of a Macintosh file that contains the actual data of the document.
See alsoresource fork.

data rate
In video, the rate at which data must be transferred in order for the video to
play smoothly without interruption. The data rate (also called “bit rate”) for a
movie is measured in kilobytes per second (K/s or KB/s). It can be calculated
by dividing the size of the file (in K) by the length of the movie (in seconds).

deprecated
In the HTML 4.0 Specification, a label identifying an HTML tag or attribute as
“outdated” and discouraged from use in favor of newer constructs (often style
sheet controls).

DHTML
Dynamic HTML; an integration of JavaScript, Cascading Style Sheets, and the
Document Object Model. With DHTML, content can move across the screen
or respond to user inputs.

dithering
The approximation of a color by mixing pixels of similar colors that are avail-
able in the image palette. The result of dithering is a random dot-pattern or
noise in the image.

Document Object Model (DOM)
The browser’s internal hierarchical organization of the elements in a docu-
ment. The existence of a DOM makes page elements available for
manipulation via scripting or style sheets. Netscape Navigator’s and Microsoft
Internet Explorer’s DOMs differ significantly.

dpi
Dots per inch; in graphics, this is the measurement of the resolution of a
printed image. It is commonly (although incorrectly) used to refer to the
screen resolution of web graphics, which is technically measured in ppi
(pixels per inch). See alsoppi.

DTD
Document Type Definition; a file associated with an SGML or XML document
that defines how the tags should be interpreted and displayed by the applica-
tion reading the document. As a subset of SGML, HTML has its own DTD.

encoding
The process of converting an analog source (such as an analog audio signal)
into digital format. An encoder is the software that does the converting.

frame rate
In video, frames per second; used as a measure of video quality.