namespace foo
  protected axiom A : Prop
  axiom B : Prop
  protected constant a : foo.A
  constant b : B
  protected axioms (A₁ A₂ : Prop)
  protected constants (a₁ a₂ : foo.A)
  axioms (B₁ B₂ : Prop)
  constants (b₁ b₂ : B)
end foo

open foo
#check foo.A
#check A  -- error
#check foo.a
#check a  -- error
#check foo.A₁
#check foo.A₂
#check A₁ -- error
#check A₂ -- error
#check foo.a₁
#check foo.a₂
#check a₁ -- error
#check a₂ -- error
#check foo.B
#check B
#check foo.b
#check b
#check foo.b₁
#check foo.b₂
#check b₁
#check b₂
#check foo.B₁
#check foo.B₂
#check B₁
#check B₂