Yes; it's still reasonably broad. (MACHOs? WIMPs?) But this is still, in terms of all possible explanations for observations re rotation curves, and the Bullet Cluster etc, well defined. It includes a lot of possibilities, but also excludes.
Unreasonably narrow, rather! We have not convinced anyone, much less done the proper science, to stick to our guns so long that it is truly matter we are hunting to explain this phenomenon.
