The Closed Classes or Nominals are defined by enumerating their Members. owl:oneOf is used to denote this.
For example one has AI defined as a Class and one has two Artificial Intelligences. One is EVA which is an AI and the other is Cabal which is also an AI. Then one defines another Class which is AI Online and one states which AIs are online.
With Description Logic this simple Fact can be stated by saying that AIOnline is a Class which is a Subclass of enumerated Class or Nominal where one enumerates all the Individuals that belong to this Class and they are in curly braces.
:AI a owl:[Class](/blog/619/) ;
:EVA a :AI .
:Cabal a :AI .
:AIOnline a owl:[Class](/blog/619/) :
owl:oneOf
(:EVA,
:Cabal) .
DL:
AIOnline ⊑ {EVA, Cabal}