File with an .MRK extension contains information stored in a plain text format, on the order of photo printing, in case of printing directly from a digital camera. MRK files are usually stored on the camera’s drive in the /MISC sub-directory, with a default name – AUTPRINT.MRK.

The MRK format is compliant with the Digital Print Order Format (DPOF) standard, the MRK printout files are stored along with the photos. Utilisation of a MRK file is possible if the printing service supports the DPOF standard.