  A new model for the shape of the prominent eccentric ringlet in the gap
exterior to Saturn's B-ring is developed based on Cassini imaging observations
taken over about 8 years. Unlike previous treatments, the new model treats each
edge of the ringlet separately. The Keplerian component of the model is
consistent with results derived from Voyager observations, and $m=2$ modes
forced by the nearby Mimas 2:1 Lindblad resonance are seen. Additionally, a
free $m=2$ mode is seen on the outer edge of the ringlet. Significant irregular
structure that cannot be described using normal-mode analysis is seen on the
ringlet edges as well. Particularly on the inner edge, that structure remains
coherent over multi-year intervals, moving at the local Keplerian rate. We
interpret the irregular structure as the signature of embedded massive bodies.
The long coherence time suggests the responsible bodies are concentrated near
the edge of the ringlet. Long wake-like structures originate from two locations
on the inner edge of the ringlet, revealing the locations of the two most
massive embedded bodies in that region. As with the Voyager observations, the
Cassini data sets showed no correlation between the width and the radius of the
ringlet as would be expected for a self-gravitating configuration, except for a
brief interval during late 2006, when the width-radius relation was similar to
those seen in most other narrow eccentric ringlets in the Solar System.
