 In some normative systems (e.g., legal systems), explicit permissions, prohibitions and obligations are given. So it would seem to be possible for there to be normative systems with gaps: systems where something is neither explicitly obligatory, impermissible, nor permissible because, say, it is neither explicitly commanded, prohibited or permitted by the relevant authority. For instance, it may well have been undecided, legally speaking, whether storing someone’s search data on a website was permissible or not prior to any new law being cast to regulate this practice. Yet \(\OB p \vee(\PE p \amp \PE \neg p) \vee \IM p\) is a thesis (“exhaustion”) of SDL (given the Traditional Definitional Scheme), which makes any such gaps impossible. There is no place for this fourth category in SDL, as it does not allow for such normative gaps (von Wright  1968).[75]  SDL is not designed to represent a notion of explicitly stated obligations, permissions, etc.