Apparently, since this discourse is from months ago, but I still see a misinformed post getting passed around, I want to give my own thoughts and feelings and information on the subject, and hopefully spread more factual information, rather than to leave people confused.
CDD is sort of a community made term (sort of being that it is a medical term, but the definition is more community based). It was supposed to encompass all dissociative disorders that cause systems as an overall term for them. Not that other dissociative disorders are not complex, but that system disorders are more complex on the rung of the theory of structural dissociation. If your disorder doesn't cause you to have alters, then you're not included in that.
People wanted a term to specifically separate dissociative disorders and the dissociative disorders that cause systems, so we could have our own category, and we don't have to clog up tags and otherwise for general dissociative disorders.
So what does fall under CDD? What are the disorders that can cause systemhood?
Before I get into this, as an aside, you do not have to have many or any alters to fall under this category. I saw this as a point of contention in the post. Those who have reached final fusion and no longer experience identity alteration, still have the disorder that caused that previous identity alteration, as there is a possibility that they could still split. There is no cure for DID and disorders alike. I just wanted to point that out there.
The disorders that fall under the community term, "CDD", are DID, C-DID/PF-DID, P-DID, OSDD-1 and UDD. I'll get into the definitions down below.
DID, also known as dissociative identity disorder, is a disorder characterized by the presence of two or more distinct personality identities. The individual also has to experience dissociative amnesia, although it does not specify what type of dissociative amnesia, seen as any gaps or skips in memory of everyday life, personal information or of past/current traumatic events. Since it is a disorder, it also must distressing or it must disturb the individual's life, causing dysfunction. And these symptoms must exist on their own and without influence from specific cultures or substances.
C-DID/PF-DID is what's known as complex or polyfragmented dissociative identity disorder. I'm unaware of whether or not you can get diagnosed with this, but it is medically recognized. This disorder has many definitions from different sources, but the main consensus is, that this disorder is characterized by complex organization and complex splitting. This can include subsystems, for certain types of trauma, side-systems, complex alters and fragments. Due to the number of fragments, a pf DID system can appear or be large, as fragments are not fully formed alters and can split and fuse easily. If you'd like to know more, I have plenty of posts on my blog discussing polyfragmentation, as well as there being a full tag right here on tumblr. There is not a specific minimum of how many alters you can have in a polyfragmented system, that is a myth.
P-DID, also known as partial DID, is something that can be diagnosed in the ICD, and is characterized by a single dominant personality identity (alter) and several alters off to the side, impacting the ANP's (apparently normal part, also known as the host) daily life. The non-dominant alters usually do not front or take control of the consciousness, but exist as intrusive feelings and emotions. These alters can be less defined, such as being like a child, disoriented in the present, or stuck replaying a traumatic event. These personality states chronically discontinue identity and self agency.
OSDD (or DDNOS in the ICD) is known as other specified dissociative disorder. OSDD-1 specifically matches the definition for DID, except for a few missing criteria. By community definition, you may have heard of OSDD-1a and OSDD-1b. 1a is similar to P-DID, having less defined and elaborated alters, but still having dissociative amnesia. 1b is having no dissociative amnesia but having well defined and elaborated alters. These definitions are only community, so if you don't fit specifically don't worry about it. And it's only OSDD-1, as it causes a system, OSDD-2 through 4 do not, so it doesn't matter to talk about them in this case.
UDD, also known as unspecified dissociative disorder, is characterized by symptoms clinically consistent with dissociative disorder but not meeting full criteria for any of the disorders in the dissociative disorder class. It is partial replacement for the previous diagnosis of OSDD. Like all disorders, it causes impairment and dysfunction in the individual's life. It is when no other dissociative disorders quite match the symptoms of the individual in question. I include this because it can include system disorders, as well as non-system dissociative disorders.
All of these fall under the group acronym of CDD, Complex Dissociative Disorders. No one is writing other disorders out of existence, nor is it meant to intentionally confuse people. It is in fact, the opposite, and to broaden and include all disorders that cause systems. Because I know most of us are sick of hearing a mouthful of acronyms, every time we would like to discuss our own community.
