Types

Traumagenic: A system that formed due to outside trauma; one of the two most prominent formation categories. There are no restrictions on the type of trauma that can cause a system since trauma is highly subjective depending on the specific person.

Endogenic: A general term for systems that did not form due to trauma; the second of the two most prominent formation categories. Many other types of system formation fall under this category. Whether a system chooses to use those specific definitions or simply endogenic is their decision.

Parogenic: A system that was intentionally formed by imagining a person within the mind and treating them as a real person until they branch off and gain independence. This term can also be known as 'tulpamancy', though since this word has religious and cultural significance, parogenic is more widely suggested for systems.

Neurogenic: A system that formed due to pre-existing conditions. Oftentimes, other mental illnesses or neurodiversities can cause this type of system. For example, autism has been believed to have an influence on plurality, as autistic people appear to be more likely to be plural systems than the rest of the population. Any mental illness or neurodiversity can influence a system and be considered under the neurogenic label.

Protogenic: A system that has been plural throughout the entire life of the body. Systems who identify this way believe that they were born this way or have been plural for as long as they can remember.

Paragenic: A system that formed due to experiences with maladaptive daydreaming. This could also fall under the umbrella of neurogenic, and it's up to the system in question to decide if the term is fitting for them personally or not. 

Pariogenic: A system that consists of soulbonds in whole or in part. Alternatively, this can be called a soulbond or gateway system, and the specific term is up to the system that may or may not choose to use it. 

Quoigenic: A system that intentionally chooses to not disclose their origins. This could be for a variety of reasons, but once again, this is the choice of the system at the end of the day. 

Adaptive: A system that originally formed due to a reason unrelated to trauma only to later shift functionality to cope with outside adversity. A system of this type could choose to identify as the specific type of initial origin, mixed origins, or simply adaptive. 

Mixed Origins: A system with multiple factors that played a part in their formation as plural. Any combination of types of origin can play a part here, and it's a system's choice individually whether or not they choose to disclose these various factors. 

Cryptogenic: A system of unknown origins. Systems that do not know how they form or do not wish to learn the truth may use this term. This could also be used for a system that could also fall under the quoigenic category. 

Polyfragmented: A system with many members. The definition has fluctuated with time, but most cite it as a system with 100+ members.

Questioning: Someone questioning whether or not they are plural. 

Multiple Personality Disorder (MPD): A disorder that was previously diagnosed on anyone who showed signs of having multiple identities living within a shared body. This term is frowned upon at present due to its inaccuracy and stigma, and the disorder's label has been retired for over thirty years. These days, this diagnosis has been replaced with DID.

Dissociative Identity Disorder (DID): A dissociative disorder with (1) distinctive headmates and (2) gaps in the memory between switches. This, much like OSDD, can only be diagnosed if a system is in chronic distress or disorder due to being plural. If the other two criteria are present but there is no distress, no diagnosis can be made. The diagnosis also cannot be made if symptoms appear as a result of substance use or are explained by a cultural practice.

Other Specified Dissociative Disorder Subtype 1 (OSDD-1): A disorder similar to DID but lacking in one of the two primary diagnostic criteria. Distress or disorder must be present for a diagnosis. There are three other subtypes of OSDD, but only OSDD-1 has to do with plurality.

OSDD-1A: A dissociative disorder with firm amnesiac barriers between headmates, but the headmates are much less defined and are often viewed as facets of a single identity. Note: this is not an official diagnosis but a community term carried over from OSDD-1's predecessor, DDNOS. A system that falls under this classification will only be diagnosed with OSDD-1. 

OSDD-1B: A dissociative disorder with distinctive headmates but no amnesia between switches. The memory pool is continuous and easier to access. Note: this is not an official diagnosis but a community term carried over from OSDD-1's predecessor, DDNOS. A system that falls under this classification will only be diagnosed with OSDD-1. 

Partial DID (P-DID): A dissociative disorder characterized by a primary headmate being in control most of the time with others influencing to a lesser degree without fully switching with the main fronter.

Note: the difference between these disorders tends to be much smaller than most people realize. There are distinctions to be made, but they all exist on the same spectrum.

The vast majority of the time, a system that is diagnosed with a dissociative disorder experienced childhood trauma. Complex dissociative disorders (CDD; the classification that DID, OSDD-1, and P-DID fall under) are highly associated with extensive childhood trauma whether it is remembered or repressed. Some systems with CDDs will remember their trauma while others may repress it as a result of dissociative amnesia, or memories that are inaccessible as a result of intense dissociation at the time. Trauma remains prevalent regardless of if it is remembered or not though. Another major indicator of a dissociative disorder is disorganized attachment, or an insufficient support system during a stressful time for a child. If a child is not supported properly through a stressful event, then they are much more likely to develop dissociative coping mechanisms due to the lack of external aid. Systems can present with distress as in CDD diagnoses without realizing they have trauma at all, and they should be recognized and validated just the same as those who remember their trauma. Even with this emphasis on trauma, however, it is worth noting that CDDs are not trauma disorders by definition; they are dissociative disorders. Even if they are dissociative disorders stemming from trauma, they are classified as dissociative disorders because of the dissociation in the system's life acting as the root of all their symptoms.