A retract circuit for retracting a data transducer carriage assembly of a mass data storage device to a retracted position has a digital state machine that is user programmable to operate in a selected retract mode. An antenna system having a pair of diametrically-mounted elements provides interferometric cancellation for spatial and polarization nulling of interference signals. The combination of salmeterol, fluticasone proprionate, and HFA 134a may lower the risk of cardiac arrhythmias, sudden death, or hypercorticism that are sometimes associated with the simultaneous administration of a \u03b22-receptor agonist and an anti-inflammatory corticosteroid. The compiler gathers performance management data related to the network at a taper code level.