Apparatus, method and system for reading/writing data, and medium for providing data read/write program

1. Field of the Invention A data read/write apparatus records, in a root directory of a recording medium, a file "MEM***.ind" indicating the type of the recording medium, a directory "DCIM" for storing still image files, a directory "VOICE" for storing voice files, a directory "HIFI" for storing audio files, and a directory "MS***" for storing information inherent to a vendor. The rules are defined as the method for recording data in the recording medium. Hence, an audio-visual apparatus can determine the type of data stored in the loaded recording medium, recognizes the format of data in a non-conforming format, and erases the data in the non-conforming format.