Readable indelible mark on storage media

In a magnetic storage media comprising a rotatable disk having. a substantially planar substrate and a magnetizable layer deposited thereon, a method comprising:

• forming a readable indelible mark in the layer such that portions of the layer are absent from the substrate, wherein the mark is read by detecting the absence of such portions of the layer, the mark comprising a series of apertures, each aperture having a width, each aperture being separated from a neighboring aperture by a distance, the method comprising:
• forming the mark such that each of a member selected from the group consisting such widths, such distances, and such widths and such distances corresponds to a value, the method comprising:
• determining an identifying code;
• and
• determining the value for each one of the selected member such that the selected member encodes the determined identifying code.