Supply accessory for a printing machine with hidden identifier

A supply accessory installable in a printing apparatus, comprising:

• an outer housing;
• a tank, disposed at least partially within the outer housing, adapted to retain a supply of print material;
• a first conductive surface disposed on the housing;
• a second conductive surface disposed on the housing;
• and
• a conductor operatively disposed between the first conductive surface and the second conductive surface, the conductor being not exposed on an outer surface of the outer housing.

A printing apparatus, comprising:

• a supply accessory including an outer housing;
• a tank, disposed at least partially within the outer housing, adapted to retain a supply of print material;
• a first cavity and a a second cavity, defined in an outer surface of the outer housing;
• a first conductive surface disposed within the first cavity;
• a second conductive surface disposed within the second cavity;
• and
• a conductor disposed inside the outer housing between the first conductive surface and the second conductive surface;
• and
• an extendible member positioned within the printing apparatus to extend into the cavity defined in the outer surface of the outer housing when the supply accessory is installed.