For the diskette types supported, the sector length is always 512 bytes. Possible values are fd and rfd , where the r indicates raw access to the special file. X Drive number indicator. Possible values of 0 and 1 indicate drives 0 and 1, respectively. Y Diskette format indicator.
Possible values depend on the type of diskette being used.
Either a single character or a decimal point followed by numeric characters is allowed. Ten different special files are available for use with the 1.44MB, 3.5-inch diskette drive. Twelve different special files are available for use with the 2.88MB, 3.5-inch diskette drive. Ten different special files are available for use with the 1.2MB, 5.25-inch diskette drive. Regardless of the diskette drive type, an h as the suffix of the special file name forces a diskette to be treated as the highest capacity diskette supported by the drive type.