Program allows input to remain at ON status even when the condition that brought it to that status stops. Example in picture below illustrates how use of a key connected to the input IR000.00 changes IR010.01 output status to ON. By letting the key go, output IR010.01 is not reset. This is because IR010.01 output keeps itself at status ON through OR circuit (having IR000.00), and it stays in this status until key at input IR000.01 is pressed. Input IR000.01 is in I connection with the output pin IR010.01 which cancels out a condition, and resets an IR010.01 bit. Example of self-maintenance is quite frequent in specific applications. If a user was connected to IR010.01 output, START and STOP functions could be realized from two keys (without the use of switches). Specifically, input IR000.00 would be a START key, and IR000.01 would be a STOP key.