the operation of a cnc machine tool is typically controlled by a "part program" written a language known as g-code. canned cycles are similar in concept to functions in a traditional computer language, and can be compared also to g-code macros. the format for a canned cycle consists of a series of parameters specified with a letter and a numerical value. the letter is referred to as an "address". (this use of the term "address" may be unfamiliar to programmers of conventional computers. it arises because in early and primitive machine controllers, the binary representation of the letter formed a physical address at which the controller would store the value following.)