patency (plural patencies). ( 1 medicine) The degree of openness of a tube, such as a blood vessel or catheter; the relative absence of blockage. ( 2 uncountable) Obviousness; clarity.
Maximum Length: 16' with a standard cable, Up to 50' with a high quality cable. VGA is an analog signal and so as distance increases the quality will decrease. A lot of factors can determine the maximum cable length, but for low resolutions (up to 800x600) you can reach 100 feet and beyond without too much trouble. For mid-range resolutions of 1280x1024/1024x768 you can typically reach somewhere between 50 to 100 feet.
The term optical density is normally, but not always, understood to be the absolute value of the logarithm with base 10 of the power transmission factor of an optical attenuator: For example, an optical density of 3 means that the optical power is attenuated by the factor 10 3 = 1000. That would correspond to an attenuation by 30 decibels. If several attenuators are used in series, their optical densities can simply be added. The optical density is often said to be identical with the absorbance.