path table block 16 ISO-9660 compatibility primary volume descriptor block 17 ISO-9660 supplementary volume descriptor block 18 ISO-9660 terminating descriptor block 19 all zero The primary volume descriptor in the media header references the fixed compatibility root folder and readme, to help users identify applications and systems that do not use the supplementary volume descriptor. The supplementary volume descriptor indicates the UCS-2 character set and references the real directory structure. The media header should be initialized exactly as is done in the logic in this header file. No additional application data, system data, comments, dates, text, etc., should be added to the media header. Unicode file names All file names and the system ID and volume ID fields of the supplementary volume descriptor are encoded as UCS-2, big-endian. File name lengths are limited by the 8 bit file record size to 110 16 bit characters. No arbitrary limits are imposed on directory hierarchy depth or combined length of a file name and included folder name components. Readers will need to choose an appropriate limit for their environment and perform checks as necessary. As in ISO-9660-1999, version numbers are not added to file names. As in ISO-9660-1999, special meaning of the '.' and ';' characters during file name sorting is eliminated. Optional path tables Path tables consume media space with redundant information, and restrict media to a maximum of 64k folders. Readers should not reference path tables. Writers may choose to generate path tables to increase compatibility with ISO-9660 readers. Path tables must be written with the directory data (folder extents), beyond the last block of file data. Note that correct path tables cannot be generated for media containing more than 64K folders. Writers that are modifying an existing media may choose to remove existing path tables. If path tables are not present then the three related volume descriptor fields in the supplementary volume descriptor must be set to zero. Extended attributes Extended attributes are reserved for future extensions to CFS. Writers must not create extended attributes. Readers must gracefully handle extended attributes if they exist. File data must be contiguous, and restricted use of duplicate file records for multi-extent files. All data for each file must exist in one contiguous extent. This is true even when the files are represented using multiple file records. Interleaved files must not be created. Associated files must not be created. Duplicate file records are