OR interfaces?

What should

EITHER

EITHER

EITHER

EITHER mean?

interface ONE {
  one: number;
  i: string;
}
interface TWO {
  two: number;
  j: string;
}

type EITHER = ONE | TWO;

interface ONE {
  one: number;
  i: string;
}
interface TWO {
  two: number;
  j: string;
}

type EITHER = ONE | TWO;

interface ONE {
  one: number;
  i: string;
}
interface TWO {
  two: number;
  j: string;
}

type EITHER = ONE | TWO;

interface ONE {
  one: number;
  i: string;
}
interface TWO {
  two: number;
  j: string;
}

type EITHER = ONE | TWO;

EITHER

EITHER

EITHER

EITHER seems to accept anything that has

* ALL the elements of either

ONE

ONE

ONE

ONE or

TWO

TWO

TWO

TWO, along with
* zero or more elements of the other.