The ornamental design for an octagonneckhole of an apparel top, as shown and described.
FIG. 1 is a perspective front view of an octagon neck hole of an apparel top, showing a first embodiment;
FIG. 2 is a front elevation view thereof; the rear elevation view being a mirror image thereof;
FIG. 3 is a perspective front view of an octagon neck hole of an apparel top, showing a second embodiment; and,
FIG. 4 is a front elevation view thereof; the rear elevation view being a mirror image thereof.
The neck hole is shown with a symbolic break in its length. The appearance of any portion of the article between the break lines forms no part of the claimed design. The remaining broken lines are directed to environmental subject matter and form no part of the claimed design.