Typography Glossary

Page Description Language (PDL) An executable description that expresses the appearance of a typeset page or series of pages. DDL, Interpress, and PostScript are examples.

Page independence The property of a page description language that allows the pages within a document to be processed and printed in any order.

Pagination Laying out the parts of a document into pages.

Parse To decode and understand, relative to a grammar. Written and spoken language is parsed in reading or listening. Visual images can also be spoken of in these terms.

Pattern recognition The process of extracting information and structure from a signal or image, by reference to known signals or images.

Pel A picture element or pixel.

Perception Seeing and understanding objects by human beings.

Perpetua Serif typeface created by face, Gill Sans.

Persistence: of a phosphor The time it takes for the light output of a phosphor to decay to 10% of its original brightness when excited.

Persistence: of vision The property of the visual system that allows a short flash of light or exposure to an image to be perceived over a longer period of time.

Phosphor Light-emitting material such as that on the inner surface of a CRT screen, that creates an image when selectively stimulated.

Photo-offset printing A printing process in which ink adhering to a photographically processed plate is transferred to paper via one or more intermediate surfaces (rollers).

Photocomposition Typesetting method in which images of letterforms are set by photographically imaging master versions onto film or photographic paper.

Phototypesetting See Photocomposition.

Pi font A font of special symbols not in the standard character set.

Pica A unit of typographic measure, equal to 12 points, or about 1/6 inch. Also, a typewriter (monospaced) typeface with a pitch of 10 characters to the inch and a vertical spacing of six lines per inch (hence the name).

Pixel A picture element, which is also called a pel. The spot of graphical information displayed at a single location on a screen or other output device, or on paper.

Plasma display Screen-display technology that uses ionised gas (plasma) to create an image. In some plasma devices, the light emitted by the plasma is used to stimulate a phosphor, which then emits visible light.

Point A unit of measure used by printers, equal to 1/72 inch. See also Didot point.

Point size The height of a font, expressed in points.

Polarity asymmetry The property in an output device that results in changes in shape when image polarity is reversed.

Polygons A straight-line representation sometimes used to express typefaces in outline form.

Portrait orientation A vertical-format page or screen, one higher than it is wide.

Postfix The sequence of specifying instructions and data in which the operation follows the data. For example, adding one and two would be done as 1 2 +. Postfix is also referred to as reverse Polish notation. In the case of a user interface, postfix order requires that an object or objects be selected first. Then the operation to be applied is specified.

PostScript A page-description language developed by Adobe Systems, Inc.

Power spectrum The graph of the energy in the component frequencies of a signal.

Prefix The sequence of specifying instructions and data in which the operation precedes the data. For example, adding one and two would be done as + 1 2. Prefix is also referred to as Polish notation. In the case of a user interface, prefix order requires that the operation be identified, and then the operand or operands.

Proof A working copy of typeset material printed for the purpose of checking content and format and of making corrections.

Property sheet A form that describes the formatting characteristics of an object within a WYSIWYG editor/formatter. The sheet is normally hidden, but may be made visible for inspection or modification.

Proportional spacing Printing in which each letter or symbol occupies an amount of horizontal space that depends upon its design.

Psychology That branch of science that studies the cognitive, perceptual, and behavioural characteristics of human beings.

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A BRIEF HISTORY OF TYPE
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LOGO TYPE GUIDE
MIXING TYPE
TYPOGRAPHY SOFTWARE
TYPE CHOICE

Sources:

Rubinststein, Richard. [1988] Digial Typography: An Introduction to Type and Composition for Computer System Design. Addison-Wesley Publishing Company.
Blue Dot's typoGRAPHIC.
The comp.fonts FAQ.

There have been .
© Kevin Woodward 1997.

	Page Description Language (PDL)	An executable description that expresses the appearance of a typeset page or series of pages. DDL, Interpress, and PostScript are examples.
	Page independence	The property of a page description language that allows the pages within a document to be processed and printed in any order.
	Pagination	Laying out the parts of a document into pages.
	Parse	To decode and understand, relative to a grammar. Written and spoken language is parsed in reading or listening. Visual images can also be spoken of in these terms.
	Pattern recognition	The process of extracting information and structure from a signal or image, by reference to known signals or images.
	Pel	A picture element or pixel.
	Perception	Seeing and understanding objects by human beings.
	Perpetua	Serif typeface created by face, Gill Sans.
	Persistence: of a phosphor	The time it takes for the light output of a phosphor to decay to 10% of its original brightness when excited.
	Persistence: of vision	The property of the visual system that allows a short flash of light or exposure to an image to be perceived over a longer period of time.
	Phosphor	Light-emitting material such as that on the inner surface of a CRT screen, that creates an image when selectively stimulated.
	Photo-offset printing	A printing process in which ink adhering to a photographically processed plate is transferred to paper via one or more intermediate surfaces (rollers).
	Photocomposition	Typesetting method in which images of letterforms are set by photographically imaging master versions onto film or photographic paper.
	Phototypesetting	See Photocomposition.
	Pi font	A font of special symbols not in the standard character set.
	Pica	A unit of typographic measure, equal to 12 points, or about 1/6 inch. Also, a typewriter (monospaced) typeface with a pitch of 10 characters to the inch and a vertical spacing of six lines per inch (hence the name).
	Pixel	A picture element, which is also called a pel. The spot of graphical information displayed at a single location on a screen or other output device, or on paper.
	Plasma display	Screen-display technology that uses ionised gas (plasma) to create an image. In some plasma devices, the light emitted by the plasma is used to stimulate a phosphor, which then emits visible light.
	Point	A unit of measure used by printers, equal to 1/72 inch. See also Didot point.
	Point size	The height of a font, expressed in points.
	Polarity asymmetry	The property in an output device that results in changes in shape when image polarity is reversed.
	Polygons	A straight-line representation sometimes used to express typefaces in outline form.
	Portrait orientation	A vertical-format page or screen, one higher than it is wide.
	Postfix	The sequence of specifying instructions and data in which the operation follows the data. For example, adding one and two would be done as 1 2 +. Postfix is also referred to as reverse Polish notation. In the case of a user interface, postfix order requires that an object or objects be selected first. Then the operation to be applied is specified.
	PostScript	A page-description language developed by Adobe Systems, Inc.
	Power spectrum	The graph of the energy in the component frequencies of a signal.
	Prefix	The sequence of specifying instructions and data in which the operation precedes the data. For example, adding one and two would be done as + 1 2. Prefix is also referred to as Polish notation. In the case of a user interface, prefix order requires that the operation be identified, and then the operand or operands.
	Proof	A working copy of typeset material printed for the purpose of checking content and format and of making corrections.
	Property sheet	A form that describes the formatting characteristics of an object within a WYSIWYG editor/formatter. The sheet is normally hidden, but may be made visible for inspection or modification.
	Proportional spacing	Printing in which each letter or symbol occupies an amount of horizontal space that depends upon its design.
	Psychology	That branch of science that studies the cognitive, perceptual, and behavioural characteristics of human beings.