2004

Glossary | 857
symbol A representation of an item commonly used in drawings. In AutoCAD
symbols are inserted in drawings as blocks.
symbol library A collection of block definitions stored in a single drawing file.
symbol table See definition table and block definition table.
system variable A name that AutoCAD recognizes as a mode, size, or limit. Read-
only system variables, such as DWGNAME, cannot be modified directly by the user.
template drawing A drawing file with preestablished settings for new drawings such
as acad.dwt and acadiso.dwt; however, any drawing can be used as a template. See also
initial environment.
temporary files Data files created during an AutoCAD session. AutoCAD deletes the
files by the time you end the session. If the session ends abnormally, such as during a
power outage, temporary files might be left on the disk.
tessellation lines Lines that help you visualize a curved surface.
text style A named, saved collection of settings that determines the appearance of
text characters—for example, stretched, compressed, oblique, mirrored, or set in a
vertical column.
texture map The projection of an image (such as a tile pattern) onto an object (such
as a chair).
thaw A setting that displays previously frozen layers. See also freeze. (LAYER)
thickness The distance certain objects are extruded to give them a 3D appearance.
(PROPERTIES, CHPROP, ELEV, THICKNESS)
tiled viewports See model viewports.
TILEMODE A system variable that controls whether viewports can be created as
movable, resizable objects (layout viewports), or as nonoverlapping display elements
that appear side-by-side (model viewports). See also viewport.
toolbar Part of the AutoCAD interface containing icons that represent commands.
tracking A way to locate a point relative to other points on the drawing.
transparent command A command started while another is in progress. Precede
transparent commands with an apostrophe.
UCS See user coordinate system (UCS).
UCS icon An icon that indicates the orientation of the UCS axes. (UCSICON)
user coordinate system (UCS) A user-defined coordinate system that defines the
orientation of the X, Y, and Z axes in 3D space. The UCS determines the default
placement of geometry in a drawing. See also world coordinate system (WCS).
vector A mathematical object with precise direction and length but without specific
location.
vertex A location where edges or polyline segments meet.
view A graphical representation of a model from a specific location (viewpoint) in
space. See also viewpoint and viewport. (VPOINT, DVIEW, VIEW)
tessellation
lines
UCS icon