The RGB values can be changed dynamically. The resource manager that deals with Xdefaults has many strings and string comparisons to deal with. By representing each string as an integer then operations are faster. These integers are called Quarks . Most requests do not generate replies.
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It is a single block of data sent over a connection. They all have unique identifiers associated with them for naming purposes. The lifetime of a resource is bounded by the lifetime of the connection over which the resource was created. Red, green, and blue intensity values are used to define a color. These values are always represented as 16 bit unsigned numbers, with zero the minimum intensity and 65535 the maximum intensity.