Self-referencing printhead assembly

A printhead assembly comprising:

• at least one printhead integrated circuit having a plurality of ink ejection nozzles;
• and
• an ink distribution support mounting the, or each, printhead integrated circuit, the ink distribution support being arranged, in use, to distribute ink to the nozzles, the printhead assembly being arranged to be mounted to a printer at the ink distribution support,
• wherein the ink distribution support is provided with at least one reference feature, the, or each, reference feature serving to provide information on the location of the nozzles upon mounting of the printhead assembly to the printer, and
• the at least one reference feature is a flat surface of a plurality of corners of the ink distribution support.