For information regarding the competition format, scoring, rules and I/0 for the System track you can have a look at the related ASPCOMP 2015 page.
The only update with respect to 2015 is the score computation for Optimization problems. In this year two scores are computed: the first score counts only confirmed optimal solutions, while the second score is based on solution quality as computed in 2015. (there will be two awards based on these two scores, see Results, where this score are referred to S1 and S2, respectively.)