Answer:

Orthodox Elliott Wave recognizes only two types of Triangles - Expanding and Contracting and allows no variational possibilities. NEoWave theory identifies a third, Neutral type (see definition below in previous Question of the Week), plus allows two variational possibilities for each due to NEoWave Reverse Alternation (see prior Question of the Week for information on that subject).

Each type is determined by which leg (wave-a, c or e) is the longest and each variation is determined by whether alternation occurs in the "standard" or "reverse" way. For example, in a standard Contracting Triangle (where wave-a is the longest leg in the direction of the trend), wave-b is always larger than wave-d. The same pattern with NEoWave Reverse Alternation will have wave-d larger than wave-b. This creates a formation with the behavior characteristics of a Contracting Triangle, but not the appearance or channeling of one. A standard Expanding Triangle contains a d-wave that is larger than the b-wave, but when NEoWave Reverse Alternation is present the opposite exists. This again will create a pattern with the behavior of an Expanding Triangle but not the channeling of one; as a result, most misinterpret such action. A NEoWave Neutral Triangle occurs when wave-c is the longest leg of the pattern. Wave-b in a "standard" Neutral Triangle is smaller than wave-d, but the opposite occurs when NEoWave Reverse Alternation is present.

With three (instead of two) primary Triangle types under NEoWave theory, plus with each allowed to possess standard or Reverse Alternation, that means under NEoWave theory there are a total of six variational, Triangle possibilities.