I concur with 220. The marked conductor is your neutral:
400.22 Grounded-Conductor Identification One conductor of flexible cords that is intended to be used as a grounded circuit conductor shall have a continuous marker that readily distinguishes it from the other conductor or conductors. The identification shall consist of one of the following methods ...
(A) Colored Braid. A braid finished to show a white or gray color and the braid on the other conductor(s) finished to show a readily distinguishable solid color or colors.
(B) Tracer in Braid. A tracer in a braid of any color contrasting with that of the braid and no tracer in the braid of the other conductor(s). No tracer shall be used in the braid of any conductor ... that contains a conductor having a braid finished to show white or gray.
(C) Colored insulation. A white or gray insulation on one conductor and insulation of a readily distinguishable color(s) on the other conductor(s) for cords having no braids on the individual conductors.
(D) Colored Separator. A white or gray separator on one conductor and a separator of a readily distinguishable solid color on the other conductor(s) of cords having insulation on the individual conductors integral with the jacket.
(E) Tinned Conductors. One conductor having the individual strands tinned and the other conductor(s) having the individual strands untinned for cords having insulation on the individual conductors integral with the jacket.
(F) Surface Marking. One or more ridges, grooves, or white stripes located on the exterior of the cord so as to identify one conductor for cords having insulation on the individual conductors integral with the jacket.