SRFI-46 and R6RS both allow a fixed number of tail patterns following an ellipsis in a syntax-rules pattern:
(P1 ... Pk Pe <ellipsis> Pm+1 ... Pn)
R6RS further allows dotted tail patterns
(P1 ... Pk Pe <ellipsis> Pm+1 ... Pn . Px)
where Px only matches a dotted list.
Do we allow either or both of these extensions?