Non blanchable erythema of skin is classified as which stage of decubitus ulcer?

The four stages of pressure ulcer formation are as follows: Stage I, nonblanchable erythema of intact skin; Stage II, paial-thickness skin loss involving epidermis or dermis, or both; Stage III, full-thickness skin loss, but not through the fascia; and Stage IV, full-thickness skin loss with extensive involvement of muscle and bone. Ref: Schwaz's principle of surgery 9th edition, chapter 9.