In 13250, an association role (represented by an  element)
represents the involvement of a certain topic in a certain association. It
has a 'type' attribute which represents the class to which the role
belongs. There is thus a kind of type-instance relationship between the
role type and the (individual) role. A role type can be thought of as the
set of all similar involvements in associations. Thus "husband" (for
example) is a *role type*, not a *role*.
Roles correspond to C-nodes. Role types correspond to R-nodes. As far as I
understand, "R" expands to "role type". This *is* confusing. I would
suggest that the RM either sticks to the same terminology all the way, or
else avoids it altogether.
You should look at the terminology used in the SAM, which is much closer to
13250.