Web file extensions and file conventions - web presence provider abitmark.com

Some Observations on
File Naming Conventions.

Since many of our customers have expressed the need to know more about file naming conventions, we offer these observations to better understand the intricacies of file naming.
Typically, development of a Web site is done locally on a PC or Macintosh and then up-loaded to a server as the final "publishing" step. If the server runs a different operating system than the local development system, transferring the site to the server may break local URL links.

One example of this is the strict filename upper and lower case sensitivity in UNIX, the type of server we use. If you have an image file named "Bitmark1.gif" and you reference that file as <a href "bitmark1.gif"> the image will work when testing on Macintosh or Windows. On a UNIX server, however, you will get a broken .gif because UNIX enforces stricter case sensitivity than the Macintosh or Windows. Other examples are characters, which can appear in filenames on one system but not on another.

For example, the filename "<nov-96>.gif" is valid on Macintosh and UNIX but not on Windows because of the greater than and less than "<>" characters. If you transfer a Web site containing this file to an NT server, the links to this file will be broken.

Yet another example is differing filename extensions. For HTML, JPEG, MPEG, and PING files:

Macintosh and UNIX require the filename extensions "html", "jpeg", "mpeg", and "ping";

while Windows requires "htm", "jpg", "mpg", and "png".

Thus, it is clear that different file systems have different restrictions on filenames. The maximum length of the filename, valid characters, punctuation and sensitivity to upper and lower case letters, all vary.

To overcome these restrictions, we highly recommend using the file specification as contained in ISO 9660 for all your files, no matter where you create them, but use only lower case letters and whenever possible use the 8.3 file naming format.

8.3 Filename and Length

ISO 9660

ISO 9660 is an international specification for filenames, which will be readable by any system. It is a good choice if you are unsure what platform/servers might need to access, store, or transfer your files.

ISO 9660: "8.3" filename:
A maximum of 8 letters and/or numbers followed by a period and a three-letter extension;
e.g.: bitmark1.htm.

Recommendation:

In light of these differences we highly recommend that you use only lower case letters and/or numbers for all your files and name all your files according to the 8.3 file system except for your first page (or home page) which HAS to be called:

index.html

that is the ONLY file with a 4-letter extension!

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