1. A programmer for wire number programming of the elements of a plural-rung ladder diagram in random order, said rungs having any desired numbers and combinations of control elements such as input devices and series and/or parallel contacts, and each rung terminating in a controlled element such as a control coil or output device comprising: a read-write memory having a plurality of data word set storage locations; encoding means operable to encode a wire number program for said plurality of rungs of the ladder diagram comprising a first data word set comprising the input wire number to a first element, the first element number, and the output wire number from the first element when said first element is either a series element or the last one of a group of parallel elements or no output wire number when said first element is other than the last one of a group of two or more parallel elements; said encoding means being further operable following entry of said first data word set in said memory to encode a second data word set comprising the input wire number to a second element that is the same as said output wire number from the first element when said first element is either a series element or the last programmed one of a group of parallel elements or is the same as said input wire number to said first element when said first and second elements are parallel elements, the second element number, and the output wire number from the second element when said second element is either a series element or the last one of a group of parallel elements or no output wire number when said second element is other than the last programmed one of a group of two or more parallel elements or a controlled element; said encoding means being further operable to encode similarly three-data-word sets for any desired number of series elements and the last one of a group of parallel elements or two-data-word sets for any desired number of additional elements that are other than the last programmed one of a group of parallel elements or controlled elements; said programming being subject to the requirement that the programming may be random as to the data word sets in different rungs with the limitation that the programming of each rung must be unidirectional and progressive toward its controlled element with respect to the data word sets of series elements and groups of parallel elements but need not be successive with respect to the data word sets of any given rung; selectively-operable entry control means; and logic circuit means responsive to selective operation of said entry control means following each said encoding of a data word set for storing the respective data word set in a predetermined plural data word location in said memory with the plural data word locations for the successively encoded data word sets being in advancing relation in said memory; and special code generating means comprising first code generating means for generating a first code indicative of an OR-logic instruction whenever any control element but the last one of a plurality of parallel control elements is stored in the memory.