2004

846 | Glossary
ambient light Light that illuminates all surfaces of a model with equal intensity.
Ambient light has no single source or direction and does not diminish in intensity over
distance.
angular dimension A dimension that measures angles or arc segments and consists
of text, extension lines, and leaders. (DIMANGULAR)
angular unit The unit of measurement for an angle. Angular units can be measured
in decimal degrees, degrees/minutes/seconds, grads, and radians.
annotations Text, dimensions, tolerances, symbols, or notes.
anonymous block An unnamed block created by a number of features, including
associative and nonassociative dimensions.
ANSI For American National Standards Institute. Coordinator of voluntary standards
development for both private and public sectors in the United States. Standards
pertain to programming languages, Electronic Data Interchange (EDI), telecommuni-
cations, and the physical properties of diskettes, cartridges, and magnetic tapes.
anti-aliasing A method that reduces aliasing by shading the pixels adjacent to the
main pixels that define a line or boundary. See also aliasing.
approximation points Point locations that a B-spline must pass near, within a fit
tolerance. See also fit points and interpolation points.
array 1. Multiple copies of selected objects in a rectangular or polar (radial) pattern.
(ARRAY) 2. A collection of data items, each identified by a subscript or key, arranged
so a computer can examine the collection and retrieve data with the key.
arrowhead A terminator, such as an arrowhead, slash, or dot, at the end of a
dimension line showing where a dimension begins and ends.
ASCII For American Standard Code for Information Interchange. A common numeric
code used in computer data communications. The code assigns meaning to 128
numbers, using seven bits per character with the eighth bit used for parity checking.
Nonstandard versions of ASCII assign meaning to 255 numbers.
aspect ratio Ratio of display width to height.
associative dimension A dimension that automatically adapts as the associated
geometry is modified. Controlled by the DIMASSOC system variable. See also nonasso-
ciative dimension and exploded dimension.
associative hatch Hatching that conforms to its bounding objects such that
modifying the bounding objects automatically adjusts the hatch. (BHATCH)
attenuation The diminishing of light intensity over distance.
attribute definition An object that is included in a block definition to store alpha-
numeric data. Attribute values can be predefined or specified when the block is
inserted. Attribute data can be extracted from a drawing and inserted into external
files. (ATTDEF)
attribute extraction file An ASCII text file to which extracted attribute data is
written. The contents and format are determined by the attribute extraction template
file. See also attribute extraction template file.
sample
arrowheads