Polygon vs. Polyline Swatch In A Legend To Represent A Boundary

Discussion created by sfadum on Jan 10, 2013
I have a map which is showing the boundary of a watershed.  My data is stored in a polygon feature class.  I am just wondering if anyone knows the 'cartographic standard' on how this should be represented in my legend.... Is it OK to use a polygon (ie. box) as the swatch for my legend, or since the polygon only represents the boundary of the catchment, is the best practice here to use a single polyline in the legend.