Uses the data in the address field, not as an address, but as a constant that is needed by the program. An example is a routine counting up to 10, which may have the constant '10' supplied in the address field of an instruction. Although the address field cannot hold numbers as large as those that can be stored as data in a memory location, because space has to be left for the operation code field, this is a particularly convenient method of loading constants into the accumulator.