984 Ladder logic requires one word of either 16-bit or 24-bit memory to uniquely identify each node in a network application program. Contacts and coils occupy one node, and therefore one word. Instructions, which usually comprise two or three nodes, require two or three words, respectively. Other elements that control program scanning such as the start of a network, beginning of a column and horizontal shorts, all use one word of user logic memory as well. Vertical shorts do not consume any words of user memory. For a complete list of all the 984 ladder logic elements and instructions, along with the total number of nodes they consume, please reference the Modicon Ladder Logic Block Library User Guide (part number 840USE10100).