Ash - the residue that is left after soot and other elements have been oxidized or combusted.

Backpressure - the pressure in an exhaust system caused by pipe bends, silencers, or other restrictions to the exhaust flow.

Balance Point - the point at which the amount of soot being collected is equal to the amount of soot being oxidized.

Catalyst - an entire device consisting of a filter, a precious metal coating, and a surrounding shell. It is by definition, a compound, element or other substance that encourages a reaction to take place between two or more elements or compounds, without changing or becoming part of the reaction itself. In exhaust technology a catalyst is generally a formulation of precious metals and/or base metals. Their function is normally to promote an oxidation process.

Data logger - a small computer which is able to store signals from sensors against time.

Duty Cycle - the normal type of duty that a vehicle performs at regular intervals. For example, a park and ride bus would have a very predictable route and short cycle frequency compared to a long distance haulage truck.

Particulate - this is any form of fine dust, however particulate has become the term for diesel engine derived soot or dust less than10 microns in diameter.

Diesel Particulate Filter - a filter which physically removes fine particulates from an exhaust stream can be referred to as a "trap", "filter", "particulate trap", "soot trap", "soot filter", "catalyzed trap", or "regenerative trap".

Regeneration - when soot is oxidized and reduced to ash within the filter, the filter is undergoing an "automatic" process that brings its condition close to optimum.

Active Regeneration - when soot is oxidized and reduced to ash within the filter and the oxidization process is initiated by an outside source (such as electricity).

Passive Regeneration - when soot is oxidized and reduced to ash within the filter, the filter is undergoing and "automatic" process that bring sits condition close to optimum.

Filter Assembly - houses the inlet section, outlet section, and filter center body.

Inlet Section - takes in exhaust from the vehicle.

Filter Center Body - is Silicon Carbide. The filter center body traps the particulate matter from the exhaust and stores it as soot until regeneration.

Thermocouple - is a device that converts temperature to an electrical output. This output can be interpreted and stored by a small computer.

Backpressure Monitor - a signal lamp to warn the driver of increased backpressure in the filter assembly detected by pressure switch mounted before the filter center body.