# Joliet

> file system

**Wikidata**: [Q1571971](https://www.wikidata.org/wiki/Q1571971)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Joliet_(file_system))  
**Source**: https://4ort.xyz/entity/joliet

## Summary
Joliet is a file system extension to ISO 9660 that allows longer filenames and Unicode characters. It was developed by Microsoft to overcome the 8.3 filename limitations of standard ISO 9660.

## Key Facts
- Joliet is an extension to the ISO 9660 file system standard
- It supports filenames up to 64 characters in length
- The system uses Unicode (specifically UCS-2) for international character support
- Joliet was created by Microsoft to address filename limitations in standard ISO 9660
- It maintains backward compatibility with standard ISO 9660 systems
- The extension is commonly used on CD-ROMs and DVDs
- Joliet filenames are stored in a separate directory structure from standard ISO 9660

### Q: What problem does Joliet solve?
A: Joliet solves the filename length and character set limitations of standard ISO 9660 by allowing filenames up to 64 characters and supporting Unicode characters, enabling international language support and more descriptive filenames.

### Q: How does Joliet maintain compatibility with standard ISO 9660?
A: Joliet maintains compatibility by storing files in both the standard ISO 9660 directory structure (with 8.3 filenames) and the Joliet directory structure (with long Unicode filenames), allowing both systems to access the disc.

### Q: What is the maximum filename length in Joliet?
A: Joliet supports filenames up to 64 characters in length, significantly longer than the 8.3 character limit of standard ISO 9660.

### Q: What character encoding does Joliet use?
A: Joliet uses Unicode (specifically UCS-2 encoding) to support international characters and languages beyond the basic ASCII character set.

### Q: Who created the Joliet file system?
A: Microsoft developed the Joliet file system extension to address the limitations of standard ISO 9660 for their Windows operating systems.

## Why It Matters
Joliet revolutionized optical disc file systems by breaking through the severe filename limitations that had plagued CD-ROM technology since its inception. Before Joliet, users were constrained to the archaic 8.3 filename format (eight characters, a period, and a three-character extension), which made organizing and identifying files on optical media cumbersome and confusing. By introducing support for longer filenames and Unicode characters, Joliet enabled more intuitive file organization and true international language support on CD-ROMs and DVDs. This was particularly crucial as software distribution, multimedia content, and data archiving moved increasingly to optical media in the 1990s and early 2000s. The backward compatibility feature ensured that Joliet discs would work on both modern systems and older equipment, making it a practical and widely adopted solution that became the de facto standard for long filenames on optical media.

## Notable For
- First widely adopted extension to ISO 9660 that supported long filenames
- Introduced Unicode support to optical disc file systems
- Maintained seamless backward compatibility with standard ISO 9660
- Became the standard for Windows-based CD/DVD mastering software
- Enabled practical international distribution of optical media content

## Body
### Technical Implementation
Joliet implements its extended filename support through a parallel directory structure that coexists with the standard ISO 9660 directory tree. While the primary volume descriptor points to the standard ISO 9660 directory, a secondary volume descriptor points to the Joliet directory structure. This dual-directory approach ensures that both Joliet-aware and legacy systems can access the disc contents appropriately.

### Character Encoding
The system uses UCS-2 (a predecessor to UTF-16) encoding for storing filenames, which supports a wide range of international characters including those from Cyrillic, Greek, Chinese, Japanese, and Arabic scripts. This encoding choice was particularly forward-thinking for its time, as it anticipated the globalization of software and media distribution.

### Directory Structure
Joliet directories can be up to 8 levels deep (compared to the 8-level limit in standard ISO 9660), and the system supports path lengths of up to 242 characters. The directory records in Joliet include additional fields to accommodate the longer filenames and Unicode character data.

### Compatibility Considerations
When a Joliet disc is inserted into a system that doesn't support the extension, the standard ISO 9660 directory structure provides access to the files using truncated 8.3 filenames. Conversely, Joliet-aware systems can access both the standard and extended directory structures, typically preferring the Joliet names when available.

### Industry Adoption
The Joliet specification was quickly adopted by major CD/DVD burning software and mastering tools, becoming the standard method for creating discs with long filenames on Windows platforms. Its influence extended beyond Microsoft products, as it provided a practical solution that other operating systems could implement for better optical media compatibility.

## References

1. Freebase Data Dumps. 2013