Doujinshi - Let me count the ways.
15 years ago
Posts: 34
So far I have come across three ways that a manga can be marked as Doujinshi.
One method is to include the name of the source material in the name followed by the letters DJ and then the title of the work, sometimes with a Hyphen after the letters DJ.
Another method is to select Doujinshi as a Genre.
The third method is to set Dounjinshi as the Type.
Searching on the letters DJ I, currently, get 191 Pages at 50 entries a Page.
Searching on the Genre Doujinshi I, currently, get 139 Pages at 50 entries a Page.
Searching on the Type Doujinshi I, currently, get 138 Pages at 50 entries a Page.
Is there a preferred method?
Personally I like using the letters DJ in the title, after the name of the source work, in combination with the Genre.
I do not like the idea of using the Type field as this means a loss of information as to the country of origin, unless someone comes up with Chinese and Korean versions for Doujinshi.

15 years ago
Posts: 10892
Currently, all series/releases that we consider doujinshi should get all 3 of those methods. The only ones without all 3 would be some of the older ones (because no one went back searching through every single series to make sure it was up to speed in policy). Having all 3 is pretty inefficient (and people still mess up or edit series), but there currently is no unified way to mark a doujinshi. We already know that.
Realize that MU does not consider original works as doujinshi. That's our own policy. Japan has a slightly different definition for the word.
The reason for the huge difference in numbers when searching for the letters "dj" is that not all releases have an associated series entry.
A just ruler amongst tyrants