In Maude, a module can be imported as a submodule of another in three different modes: protecting, extending, including. This is done with the syntax declarations protecting ⟨ModuleExpression⟩ .
extending ⟨ModuleExpression⟩ .
including ⟨ModuleExpression⟩ . which can be abbreviated, respectively, to pr ⟨ModuleExpression⟩ .
ex ⟨ModuleExpression⟩ .
inc ⟨ModuleExpression⟩ . …