The design is the visual features of the DOOR shown in the drawings, whether those features are features of one of shape, configuration, ornament or pattern or a combination of any of these features. Drawings of the design are included, in which: FIG. 1 is an isometric view of a DOOR according to the design; FIG. 2 is a front view of the DOOR of FIG. 1, of which a back view is identical; FIG. 3 is a top view of the DOOR of FIG. 1, of which a bottom view is identical; FIG. 4 is a right side view of the DOOR of FIG. 1, of which a left side view is identical; FIG. 5 is an enlarged fragmentary view taken from a detail of the DOOR of FIG. 1; FIG. 6 is an isometric view of a DOOR, according to a first variant of the design; FIG. 7 is a front view of the DOOR of FIG. 6, of which a back view is identical; FIG. 8 is a top view of the DOOR of FIG. 6, of which a bottom view is identical; FIG. 9 is a right side view of the DOOR of FIG. 6, of which a left side view is identical; FIG. 10 is an enlarged fragmentary view taken from a detail of the DOOR of FIG. 6; FIG. 11 is an isometric view of a DOOR, according to a second variant of the design; FIG. 12 is a front view of the DOOR of FIG. 11, of which a back view is identical; FIG. 13 is a top view of the DOOR of FIG. 11, of which a bottom view is identical; FIG. 14 is a right side view of the DOOR of FIG. 11, of which a left side view is identical; FIG. 15 is an enlarged fragmentary view taken from a detail of the DOOR of FIG. 11; FIG. 16 is an isometric view of a DOOR, according to a third variant of the design; FIG. 17 is a front view of the DOOR of FIG. 16, of which a back view is identical; FIG. 18 is a top view of the DOOR of FIG. 16, of which a bottom view is identical; FIG. 19 is a right side view of the DOOR of FIG. 16, of which a left side view is identical; FIG. 20 is an enlarged fragmentary view taken from a detail of the DOOR of FIG. 16; FIG. 21 is an isometric view of a DOOR, according to a fourth variant of the design; FIG. 22 is a front view of the DOOR of FIG. 21, of which a back view is identical; FIG. 23 is a top view of the DOOR of FIG. 21, of which a bottom view is identical; FIG. 24 is a right side view of the DOOR of FIG. 21, of which a left side view is identical; FIG. 25 is an enlarged fragmentary view taken from a detail of the DOOR of FIG. 21; FIG. 26 is an isometric view of a DOOR, according to a fifth variant of the design; FIG. 27 is a front view of the DOOR of FIG. 26, of which a back view is identical; FIG. 28 is a top view of the DOOR of FIG. 26, of which a bottom view is identical; FIG. 29 is a right side view of the DOOR of FIG. 26, of which a left side view is identical; FIG. 30 is an enlarged fragmentary view taken from a detail of the DOOR of FIG. 26; FIG. 31 is an isometric view of a DOOR, according to a sixth variant of the design; FIG. 32 is a front view of the DOOR of FIG. 31, of which a back view is identical; FIG. 33 is a top view of the DOOR of FIG. 31, of which a bottom view is identical; FIG. 34 is a right side view of the DOOR of FIG. 31, of which a left side view is identical; FIG. 35 is an enlarged fragmentary view taken from a detail of the DOOR of FIG. 31; FIG. 36 is an isometric view of a DOOR, according to a seventh variant of the design; FIG. 37 is a front view of the DOOR of FIG. 36, of which a back view is identical; FIG. 38 is a top view of the DOOR of FIG. 36, of which a bottom view is identical; FIG. 39 is a right side view of the DOOR of FIG. 36, of which a left side view is identical; and FIG. 40 is an enlarged fragmentary view taken from a detail of the DOOR of FIG. 36.