(1) Ic is a set of output index cells to be activated. If an output index cell is in the dead state, it is changed to the initial state so that it becomes a live cell, and the clock t is initialized to be t_max. If an output index cell is already live, its current state remains unchanged, but its clock t is re-initialized to be t_max. If an output index cell is the special symbol nil, no output index cell is actually activated.

(2) y is the output message for the output index cells in Ic. The output could be the dummy message d, when there is no real output to the output index cells. The first output index cell that accepts this output message y will remove it from the output list of ic.