A finite graph with an assignment of nonnegative integers to vertices gives chip-firing
games. Chip-firing games determine languages (sets of words) called the record sets
of legal games. Björner, Lovász and Shor found several properties that
are satisfied by record sets. In this paper, we will find two more properties
of record sets. Under the assumption that the record set is finite and the
game fires only two vertices, these properties characterize the record sets of
graphs.