Overview
ISO/IEC 13490-2:1995 defines the volume and file structure for read-only and write-once compact disc media (CD-WO, hybrid CD-WO, CD-ROM) intended for information interchange. It specifies the format and system requirements that allow different information-processing systems to exchange files reliably across CD media. The part emphasizes attributes of volumes and partitions, file placement and attributes, relationships among files and file sets, and levels of medium interchange.
Key topics and technical requirements
- Volume & partition attributes: rules for describing a volume, relationships among volumes in a volume set, and how partitions are defined on CD media.
- Directory and Path Table records: precise field layouts (lengths, offsets) for Directory Records and Path Table Records including fields such as Location of File Section, Data Length, Recording Date/Time, File Flags, File Identifier and File Version Number.
- File placement and multi‑extent support: handling of single and multiple file sections (the “MF” extended attribute) and special values (e.g., #FFFFFFFF meaning unrecorded content treated as zeros).
- File flags and semantics: interpretation of individual bits (Existence, Directory, Associated file, Record, Protection, Version, Alias, Multi-Extent) that control file behavior and record interpretation.
- Interleave and recording modes: fields for File Unit Size and Interleave Gap Size defining interleaved versus non-interleaved recording.
- Extended attributes framework: short and long form extended attribute formats, plus a standardized set of attributes including:
- CS (Character Set Information)
- PD (Padding)
- PM (Alternate Permissions)
- RF (Record Structure)
- TF/TI (File/Information Times)
- FC (File Contents)
- CE (Continuation)
- MF (File Section Description)
- UX (ISO 9945-1 File Attributes)
- XR (Previously recorded Directory Record)
- Implementation and Application use areas (SU, AU)
- Character set handling: “CS” extended attribute and escape sequence support per ISO/IEC 2022.
- Compatibility notes: differences and extensions relative to ISO 9660 (e.g., separate file version field, symbolic links allowed).
Applications and who uses it
- Software developers and firmware engineers building CD authoring, mastering or burning tools for CD‑WO and CD‑ROM.
- File-system implementers and OS integrators that need to read/write interchange CD formats.
- Archival and data preservation professionals using write-once media for long-term data interchange and distribution.
- Hardware manufacturers of CD drives and embedded systems requiring accurate logical block layouts and metadata handling.
- Developers of cross-platform distribution workflows (hybrid discs combining formats).
Related standards
- ISO 9660 (baseline CD-ROM file system) - ISO/IEC 13490 extends and refines aspects of ISO 9660.
- ISO/IEC 2022 (character set escape sequences) - referenced for CS attribute handling.
- ISO 9945-1 (POSIX file attributes) - referenced via the “UX” extended attribute.
Keywords: ISO/IEC 13490-2:1995, CD‑WO, CD‑ROM, volume and file structure, extended attributes, Directory Record, Path Table, file flags, multi‑extent, character set.