"Difficulty Index": A measurement of how difficult the position is along with the risk of initial pain/difficulty.
Easy - Comfortable, typically low-intensity, and easy to do even when sleep-deprived/tired. Usually has a low risk of pain (likely not anal penetration). An example could be a handjob (if that is considered a sex position) or perhaps spooning.
Medium - Enough intensity picks up that the position is no longer an ideal option when sleep-deprived/tired. Lying down is no longer the only option, although it is unlikely much flexibility will be needed. Possible examples include the standard missionary and Doggy Style.
Hard - Things may get intense, especially for the female side -- who is likely taking a flexibility-intensive position. Some examples include Butterfly and Scissors.
Excruciating - High acrobatics skills are required for at least one party and perhaps even for both sides. Notable examples include but are not limited to Hanger, Piledriver, and Wheelbarrow.

Posted: 16 Dec 00:46