1. A printing apparatus, comprising: an acquisition unit configured to acquire identification information for identifying a file stored in an external device connected to the printing apparatus; a determining unit configured to determine whether or not the identification information acquired by the acquisition unit is described using a predetermined character code set; a generation unit configured to generate, in a case where said determination unit determines that the identification information acquired by the acquisition unit is not described using the predetermined character code set, substitute identification information, described using the predetermined character code set, of the identification information acquired by the acquisition unit, wherein the generation unit generates the substitute identification information without converting the identification information using a conversion table, wherein the substitute identification information includes a predetermined affix not derived from the identification information and numerical value which is incremented whenever the substitute identification information is generated by the generation unit, and wherein the generation unit does not generate the substitute identification information in a case where said determination unit determines that the identification information acquired by the acquisition unit is described using the predetermined character code set; a storing unit configured to store the substitute identification information generated by the generation unit and the identification information acquired by the acquisition unit in association with each other; and a display unit configured to display on a display section the substitute identification information stored by the storing unit in a case where said determination unit determines that the identification information acquired by the acquisition unit is not described using the predetermined character code set, and to display the identification information acquired by the acquisition unit on the display section in a case where said determination unit determines that the identification information acquired by the acquisition unit is described using the predetermined character code set, wherein at least one of the acquisition unit, the determining unit, the generation unit, the storing unit, and the display unit is implemented, at least in part, by a hardware processor.