The media header has the following layout: 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.
Writers may choose to generate path tables to increase compatibility with ISO-9660 readers.
Note that correct path tables cannot be generated for media containing more than 64K folders.
All file data must precede all folder extents and path tables on media.
Writers will need to determine the last block of file data after reading the entire directory.
All files and folders written in the image must be accessible through the single directory structure referenced from the supplementary volume descriptor.
Compound file systems, such as including UDF or HFS structures, are not allowed.
Future versions of CFS may include extensions to allow storing system specific attributes such as time fields, security descriptors, access control lists, resource forks, symbolic links etc..
CFS images are only compliant with this specification when they are stored in DD or CISO (Compact ISO) format media files.
The PSP compressed ISO format is also referred to as CISO, but the file extension is CSO.
CFS writing applications should default to writing DD format media container files unless the user has specified container file options that require CISO (spanning, compression, ...).