dm4hire
Explorer
Paizo Blog said:CMD, which stands for Combat Maneuver Defense. This statistic is the DC for anyone else to perform a combat maneuver, such as bull rush, disarm, or grapple, against Valeros. This statistic is derived from his CMB +10 plus a number of other modifiers (Dexterity and deflection bonuses in this case). Note that Valeros adds his weapon training bonuses to his CMD whenever anyone tries to disarm or sunder weapons from those groups (he also adds these bonuses to combat maneuver checks made using weapons from those groups).
You improve CMD by improving your CMB. Essentially it is an oppose check but you're getting the advantage of automatically getting 10 or as he put it, taking 10. I personally would rather take the 10 than risk it. CMB is designed to favor the fighter types who will have higher scores and more likely better success at not being grappled and such.