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ISO 9660 (file naming) standards by Matt Ottewill

The ISO9660 standard was originally created to define rules for file naming and standardise the file structure of a cross platform CDROM, and to help ensure the compatibility of files moved between differing computer systems (eg Macs and PCs).

Subsequently, the rules have been used for naming web site pages and files. In recenet years these rules have evolved.

The initial ISO-9660 file naming rules (also known as 8:3)

Before Windows 98 there was Windows 95 and before that Windows 3.1 and bare bones DOS. There are still some of Windows 3.1 users around. Windows 3.1 imposes strict rules on the naming of files known as the ISO-9660 naming conventions (Unix imposes similar rules). Those who ignored these conventions excluded 3.1 and Unix end-users from viewing their projects. It was essential that web site/multimedia project folders and files were named appropriately to enable the Windows 3.1 and Unix operating systems to "see" the files.

These were the initial file naming conventions.

  1. Use 8 or fewer characters to name the file (unless you want compatibility with systems older than 10-12 years you can safely use up to 26 characters now)
  2. Use only lower case letters a-z and numbers 0-9 and the underscore character (_)
  3. Leave no spaces
  4. Always begin the name with a letter, not a number
  5. Follow the name with a period (.). NOTE: Only folders do NOT require this.
  6. Follow the period with a 3 character extension. NOTE: Folders do NOT require this.

ISO-9660 Extensions

ISO-9660 employs a three character extension at the end of a file name to determine the file type. Here are some extensions ...

  • .txt = ASCI text file
  • .htm = Hyper Text Mark-up Language file
  • .dir = Director movie
  • .dxr = Locked (protected) Director movie
  • .mov = QuickTime for Windows
  • .avi = Video for Windows
  • .wav = Wave, audio file
  • .aif = Audio Interchange File Format
  • .gif = GIF
  • .jpg = JPEG PICT
  • .swf = Shockwave file
  • .fla = Flash movie
  • .exe = An executable self running application, such as a Director projector


Inevitably there are some exceptions. For example .html is allowed.

Web site file naming today

Today, the most common situation in which files will be viewed by differing computer systems is of course on the world wide web. To be certain of compatibility it is therefore essential that you observe current file naming rules when naming the following file types ...

  • web pages
  • CSS files
  • JavaScripts
  • images
  • mp3 audio files
  • folders
  • video files
  • animation files (eg Flash)
  • pdfs
  • etc

Here are the current guidelines/rules ..

  1. Try to use 32 or fewer characters
  2. Use only lower case letters a-z and numbers 0-9 and the hyphen (-) to seperate words
  3. Leave no spaces
  4. Use relevant keyword(s) towards the beginning of the URL
  5. Always begin with a letter, not a number
  6. Follow the name with a period (.). NOTE: Only folders do NOT require this.
  7. Follow the period with a 3 character extension. NOTE: Folders do NOT require this.

NOTE: If you are linking files which will be downloaded rather than viewed in the browser, you may not need to observe the rules so strictly, except that you should be careful to always include the file extension (eg .mp3).

Mac file naming


Apple's old file naming system was called HFS (Hierarchical Filing System) and can happily "see" files named according to the ISO-9660 conventions but does not require them for itself. Files created on the Mac contain embedded information within their data/resource forks structure indicating the files origins and type.


Things have changed with the Unix based OSX. Use extensions and assume files handle like Windows.

Unix file naming

The Unix operating system file naming system is similar to ISO-9660 but demands lower case characters only. If you want your multimedia and web projects to run on PCs, Macs and Unix systems you must acknowledge this simple rule when naming your files.

Naming files for cross platform compatibility

There will be occasions when your multimedia project files must be transferred between Macs and PCs. For example ...

  • You wish to create a hybrid CD-ROM containing PC and Mac projectors which share common linked media files (discussed later).
  • A project being developed on a PC is to be continued on a Mac.
  • A project being developed on a Mac is to be continued on a PC.

Here are some of the extensions you should use:

  • .CST = External cast
  • .MOV = QuickTime
  • .WAV = Wave audio file
  • .SWF = Shockwave file


To make an ISO 9660 cross platform disc, select this option in your CD burning software. You should observe the file naming conventions laid out below for all your files as laid out below.

Referring to filenames in Lingo scripts

Never include extensions when referring to linked external files and movies in Lingo scripts, although the files themselves must include extensions. For example ...

If a saved file is entitled menu.dir ... then call it ... movie "menu" in a lingo script.

Referring to pathnames in Lingo scripts

When referring to the location of linked files in Lingo, Director developers should remember that the Mac uses colons (:) in pathnames, and Windows uses the backslash (\). Director 7 takes care of updating pathnames automatically when projects are ported cross-platform.