A resistor in which a sliding or rolling contact moves over an exposed area of the resistive element to change the ohmic value of the output. the functional tolerance (linearity), if given, of the output is greater than plus or minus 1 percent on linear outputs. specified outputs such as sine, cosine, tangent, etc., shall be considered to be precision. for items having manually positioned taps designed to be set and fixed prior to use, see resistor, adjustable. for items with step by step variation, see rheostat and resistor, step by step. for tandem-mounted items designed to function together as an attenuator (and rated accordingly), see attenuator, variable. excludes resistor (1), variable, wire wound, nonprecision; resistor (1), variable, nonwire wound precision; and resistor (1), variable, wire wound, precision.