The Gabriel-Roiter measure for ${\tilde{\mathbb{A}}}_n$ II

Let $Q$ be a tame quiver of type ${\tilde{\mathbb{A}}}_n$ and $\text{Rep}(Q)$ the category of finite dimensional representations over an algebraically closed field. A representation is simply called a module. It will be shown that a regular string module has, up to isomorphism, at most two Gabriel-Roiter submodules. The quivers $Q$ with sink-source orientations will be characterized as those, whose central parts do not contain preinjective modules. It will also be shown that there are only finitely many (central) Gabriel-Roiter measures admitting no direct predecessors. This fact will be generalized for all tame quivers.