CLASS I - This type of specter is defined as an undeveloped form, insubstantial and difficult to see. The Class I's interaction with the physical environment is limited and enigmatic (i.e. spectral lights, voices, sounds).

CLASS II - A ghost that begins to have actual visible characteristics and can physically manipulate things (i.e. poltergeist). Class II forms tend to be vague and inconsistent, like hands or a face just floating there.

CLASS III - When a ghost begins to take an actual distinct human form (i.e. face, torso, arms) it's classified as a Class III. III's can often change their forms as well.

CLASS IV - When investigation reveals the former identity of a Class III ghost, it is reclassified as a Class IV. Usually indistinct from the chest down.

CLASS V- An ectoplasmic manifestation of definite but non-human form. Theory supposes that Class V's are formed from emotionally-charged events or locations.

CLASS VI - A non-human "animal" ghost.

CLASS VII- A Metaspecter with extra-dimensional powers far beyond human ken. Powers often include the ability to change form at will, dematerialize objects, summon pests, or possess people and animals just to name a few.