I never engineered nothing unless you count my soap-box derby car in cub scouts. But I don't believe that is exactly what they are saying in these websites. It can be looked at another way; which is by changing the requirements ever so slightly; someone can freeze up a design in perpetuity. The point these people make is that it has been studied and proven that most restrictive covenents stifle creativity while producing very little for the designer. Lon's point that the famaily of Stan Getz can buy up his copyrighted tunes and hold them in escrow forever by renewing the copyright and thereby you will never hear the works; which were clearly meant to be available by the wishes of the composer.