Plus-minus dimensioning
uses a bilateral or unilateral tolerance format, depending on the
application. Plus-minus dimension values are placed using the plus-minus
symbol (±), for example 12±0.1 or .750±.005. A bilateral tolerance is allowed
to vary in two directions from the specified dimension, as in
The dimension value
is an unequal bilateral tolerance, and the 6.5 ± 0.2 dimension value is called an equal bilateral tolerance.