The general rule in Wisconsin is: (a)  Courts will literally interpret unambiguous contracts; and (b) extrinsic evidence will be used to interpret ambiguous contracts. A recent appellate court decision applied this general rule with respect to noncompete agreements holding that the trial court’s finding that the noncompete was ambiguous was, without additional findings, not enough to find the agreement unenforceable. See

http://www.wisbar.org/res/capp/2011/2010ap000801.htm