A symbol consisting of three rational numbers that can be used to describe uniform polyhedra based on how a point 
in a spherical
triangle can be selected so as to trace the vertices of regular polygonal faces.
For example, the Wythoff symbol for the tetrahedron
is 
. There are four types of Wythoff symbols, 
, 
, 
and 
, and one exceptional
symbol, 
(which is used for the great dirhombicosidodecahedron).
The meaning of the bars 
may be summarized as follows (Wenninger
1989, p. 10; Messer 2002). Consider a spherical
triangle 
whose angles are 
, 
, and 
.
1. 
: 
is a special point
within 
that traces snub polyhedra by even
reflections.
2. 
(or 
): 
is the vertex
.
3. 
(or 
): 
lies on the arc
and the bisector of the opposite angle 
.
4. 
(or any permutation of the three
letters): 
is the incenter of the triangle 
.
Some special cases in terms of Schläfli symbols are
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(1)
|
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(2)
|
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(3)
|
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(4)
|
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(5)
|
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(6)
|
