For cutouts with a lug on one side and quite open on the other, giving option /FL_WIDTH means that these clearances are set to B -S +<xxx>. (Here, B is the width of the flange and S the thickness of the web and <xxx> the given value).
This will normally result in a cutout with total width between the lug and the opposite side equal to B+<xxx>. It is especially useful when T-bars should be inserted as described in the figure below and should be used only for cutouts with lug one side.
For cutouts with a lug on one side and quite open on the other, giving option /FL_WIDTH means that these clearances are set to B -S +<xxx>. (Here, B is the width of the flange and S the thickness of the web and <xxx> the given value).
This will normally result in a cutout with total width between the lug and the opposite side equal to B+<xxx>. It is especially useful when T-bars should be inserted as described in the figure below and should be used only for cutouts with lug one side.