I am using WinISD to calulate a rectangular/shelf vent for a cab... Is the "vent length" the length of the shelf only (sketch A)? Or is part of the corner also considered part of the "vent volume" therefore making the shelf and the calculated vent length slightly different (sketch B)? See sketch I made that hopefully helps explain my question. Grey question mark area is where I am unsure if this is "cab volume", "vent volume", or a combination of the two (as in sketch B). Thanks in advance!