On the optimality of the standard genetic code: the role of stop codons

The genetic code markup is the assignment of stop codons. The standard genetic code markup ensures the maximum possible stability of genetic information with respect to two fault classes: frameshift and nonsense mutations. There are only 528 (about 1,3% of total number) optimal markups in the set of markups having 3 stop codons. Among the sets of markups with 1,2,…,8 stop codons, the standard case having 3 stop codons has maximum absolute number of optimal markups.