*Multivariate data* (also called multidimensional or n-dimensional) consists
of some number of points, *m*, each of which is defined by an *n*-vector of
values.

Such data can be viewed as an *mxn* matrix, where each row
represents a data point and each column represents an observation (also called
a variable or dimension).

An observation may be nominal or ordinal, and may or may not have a distance metric, ordering relation, or absolute zero.

Each variable/dimension may be independent or dependent.

A *glyph* consists of a graphical entity with *p* components, each of
which may have *r* geometric attributes and *s* appearance attributes.

Typical geometric attributes include shape, size, orientation, position, and direction/magnitude of motion, while appearance attributes include color, texture, and transparency.

Attributes can be discrete or continuous, scalar or vector, and may or may not have a distance metric, ordering relation, or absolute zero.

The list below (and Figure) give examples of glyphs from the literature and attributes controlled by the multivariate data point.

- profiles [17]: height and color of bars.
- stars [45]: length of evenly spaced rays emanating from center.
- Anderson/metroglyphs [1,20]: length of rays.
- stick figure icons [39]: length, angle, color of limbs.
- trees [29]: length, thickness, angles of branches; branch structure derived from analyzing relations between dimensions.
- autoglyph [4]: color of boxes.
- boxes [21]: height, width, depth of first box; height of successive boxes.
- faces [6]: size and position of eyes, nose, mouth; curvature of mouth; angle of eyebrows.
- arrows[48]: length, width, taper, and color of base and head.
- weathervanes [18]: level in bulb, length of flags.
- circular profiles [37]: distance from center to vertices at equal angles.
- bugs [9]: wing shapes controlled by time series; length of head spikes (antennae); size and color of tail; size of body markings.
- wheels [9]: time wheels create ring of time series plots, value controls distance from base ring; 3D wheel maps time to height, variable value to radius.
- Glyphmaker [40]: user-controlled mappings.