-The third case allows building edges of desired length on any existing
-curve (selected existing edge). <b>Start Point</b> parameter is optional.
-Any point can be selected for it, the new edge will begin at the end
-of initial edge, close to the selected point. <b>Length</b> can exceed
-the initial edge's length or be negative to extrapolate existing edge
-along its curve (except bezier and b-spline curves).
+Thirdly, it is possible to build an edge of required \b Length on any existing
+\b Edge.
+
+<b>Start Point</b> parameter is optional:
+- if used, it allows selecting any existing point - in such a case the start point
+of the new edge will be chosen as start or end point of the selected \b Edge
+whatever is closest to the selected <b>Start Point</b>
+- if it is missed, the start point of the initial edge is used
+
+<b>Length</b> can exceed the length of the initial edge length or be
+negative. In this case the existing edge is extrapolated
+along its curve (except for bezier and b-spline curves).