-means of "destination", which can be a destination point (for segment
-only) or destination direction coupled with length of a segment or
-angle and radius of an arc.
+means of "destination", which can be a destination point (coupled with a radius
+or a center for an arc) or a destination direction coupled with length
+of a segment or angle and radius of an arc.
+
+\n <b>Warning:</b> When constructing an arc by its center and destination point,
+the constraint on the center is first taken into account. Therefore
+if the constraints are incompatible the destination point <b> won't lie
+on the constructed arc</b> (a warning message will be displayed).