Mac and Windows OS File/Folder naming rules

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The following list is fairly exhaustive and pulls together references from various sources. Although not mentioned explicitly, Unix seems to have few - if any - restrictions. Compliance with these conventions as assets are added to your library will allow widest use of the assets without subsequent manual intervention to re-path/name, etc. The rules take into account the use of assets on local & network hard drives, CD/DVD, removable drives and online (web/ftp) using Mac OS9/OSX and Windows OSs:

  1. Illegal filename characters, (e.g. : or ?). (All OSs).
  2. Deprecated filename characters (; and ,). (All OSs).
  3. >31 filename characters including extension. (Mac Classic).
  4. >64 filename characters including extension. (Windows: ISO9660+Joliet CD or Hybrid CD partition).
  5. No extension - extensions are mandatory for Windows and the only means for Portfolio to tell file type. (Windows, Mac OS X).
  6. Filename has >1 period - Portfolio may misinterpret extension. (Windows, Mac OS X).
  7. Extension may be wrong, i.e. not 3 characters. (Windows, Mac OS X).
  8. Illegal characters in path to file - same issue as #1 but for path. (All OSs).
  9. Deprecated characters in path to file - same issue as #2 but for path. (All OSs).
  10. Filename may not begin with a period. (Windows not allowed, Mac treats as a hidden file)
  11. Filename may not end in a period. (Windows not allowed - OS 'throws away' the trailing period when naming/reading so incorrect matching vs. Mac name)
  12. Names conflicting with some of Win OS' old DOS functions (Not allowed in either upper or lowercase and with or without a file extension or as a file extension: COM1 to COM9 inclusive, LPT1 to LPT9 inclusive, CON, PRN, AUX, CLOCK$ and NUL)
  13. Case sensitivity. Windows OSs (and IIS web servers) aren't case sensitive. Most other OSs (and web servers) are.
  14. Filenames ought not to begin with a hyphen (Unix systems my interpret the filename as a flag to a command line call).


So that's it then?
Not really, these rules are advisory - you will need to think how to apply them. For instance you may work only on Mac OS and thus don't need to worry about folder names but you will need to ensure you files - or those you may need to send to users not on Macs - have extensions. Of course, the extension needs to be appropriate - don't put '.jpg' on the end of a TIFF, for example. If you're unsure about extensions there are numerous online listing that will give these to you.

On the subject of extensions, this is one thing it's not too easy to change in Portfolio except via 'link to new file' or scripting. As 'link to new file' require you so manually set each connection, scripting is the way to go - if you can define the changes to make.

Anyway, don't feel compelled to apply all of the above rules. Rather, be aware of them and apply them as appropriate. If you are starting a new collection or re-ordering old content you're at the right point to get some discipline into the naming. If some or all of your new content comes in from external sources and is poorly named, sit down with your partners make sure good naming rules are in the contract. Then, if it's wrong, they can rename files at their time/expense - a good encouragement for them to adopt good practice from outset.

Some final thoughts
You might also consider these additional rules where older OS variants are in use:

Other Useful Links (Open in new window) - Filenaming
Wikipedia - File Name
Wikipedia - ISO9660

Question: Mac and Windows OS File/Folder naming rules [FAQ00352.htm]
Last Update:- 04 September 2007

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