โSir, what you had there was what we refer to as a Focused, Non-Terminal, Repeating Phantasm, or a Class 5 Full-Roaming Vapor โฆ a real nasty one tooโ
Classification System
โA clear list system was made in Ghostbuster RPG, which is the standard most fans go by. The class system is known mostly as list of seven classes that a paranormal event can be labeled to better understand and deal with.
These are undeveloped forms, insubstantial and difficult to see. Interaction with their environment is limited and enigmatic (i.e., spectral lights, voices and sounds, ectoplasmic vapors, etc.). Simple application of a proton pack beam is normally effective.
Manifestations focused in this time and space, Class II ghosts and up can physically manipulate things in this world. These forms are vague, inconsistent, or incomplete (i.e., floating sheets, ghostly hands, animated lips, etc.). Although a proton pack beam is normally effective, some Class II ghosts have the capacity to return attacks.
Anonymous Hauntings. Distinct human form and personality is evident, but former identity (I.E., as a living being.) is not established. If established, ghost is reassigned as Class IV. Often difficult to deal with, Class III ghosts generally possess sophisticated means of defense.
Identity is established. They have a distinct human form and personality with known identity, such as General Custer or Cleopatra. Economic disposal methods include research into the background of said entity, as well as possible communication with it.
These are Ectoplasmic manifestations of definite but non-human form. Speculation includes the theory that Class Vโs are formed from emotionally-charged events or as side effects from ritual summoning (Slimer was a by-product of the rituals that a cult held in the Sedgewick Hotelโs basement.). These typically require extensive proton pack implementation to eradicate.
Ghosts from lower life forms. A giant penguin was once seen attacking a mugger in Central Park. Later it was discovered that the penguin was a ghost. Unique solutions are often required to handle these entities, including research into habitats, allergies, natural enemies, etc.
Metaspectres. Obsessively malevolent, exceptionally powerful, and exhibiting control over subordinate forms, such entities are potentially very dangerous. These are often identified by primitive cultures as โDemonsโ. Entitles which fit this classification include Gozer and Zuul. Neutralizing them is usually a problematical undertaking at best. Most standard procedures are futile. The most realistic plan is to take measures to prevent these things from entering the sphere of influence in the first place.โ
Taken from: http://ghostbusters.wikia.com/wiki/Classification_System