Dishwasher - Definition of Posi-Track

In the past, some dishwashers featured "Posi-Track" racks. Posi-Track is defined as:

A special axle roller assembly, mounted at top rear of the rack on some dishwashers. It keeps the rack rollers properly located in their stainless steel track to reduce rack wobble and provide a more, sturdy smooth operation and quality feel.

This is not a feature on current models.