In the example illustrated on figure 4.8, the models run sequentially for the first run only and then run simultaneously. For the first run, the LAG and SEQ indices must be defined as in section 4.8.3. After the first run, the situation is similar to the one of section 4.8.1, and positive LAG must be defined for and . As their lag is positive, their corresponding first prism_get_proto will automatically lead to reading and from coupling restart files. In this case, model A has to write to its restart file explicitly by calling prism_put_restart_proto (illustrated on the figure by an orange arrow) at the end of the first run; in fact, lag being then negative, such writing is not automatically done below the last prism_put_proto of the first run.