From general movement rules: How is an inferior Silhouette determined? Is it: A) Determined by the physical volume of a silhouette. So Silhouette 2 is inferior to Silhouette 4 B) Determined by the physical height of the silhouette. So Silhouette 3 is equal to 4, but inferior to Silhouette 2. C) Determined by the numerical value of the silhouette. So Silhouette 2 is inferior to Silhouette 3
Option C, numerical comparison of the S values. I blame the confusion on Spanish vs. English bilingualism, since the corresponding phrase in Spanish is "igual o inferior".
It's not the Silhouette itself, but the Silhouette Attribute. So what solkan said, you compare the numerical values of the Attributes.
