The Register concept was introduced and removed an interim version of 4.0. There are a few places where remnants remain. Need to search for "register" and remove all spec parts. Here is an example in ebRIM 10.6.2 Matching Subject By Role:

"The following example shows a Subject that matches a subject role "ProjectLead" within the organizational context of Organization TestSubmittingOrg1 and register context of Register TestRegister1:"