transparancy and RGB()

Has any thought been given to the idea of specifying varying levels of 
transparancy?  What about the idea of specifying the transparancy level 
directly in an RGB value, such as....

p { background: rgb(20%,0%,0%,50%)} /* final value = transparancy level */

Also, in the latest version of the CSS spec, it dosn't show the 
possibility of specifying RBG values in hexadecimal anymore?  Was this an 
accidental ommision, or was it felt that too many ways of specifying 
colors would be confusing?

----------------------- Christopher P. Josephes ----------------------------
Email |  mailto:cpj1@winternet.com
Web   |  http://www.winternet.com/~cpj1/