Re: *.dat file

Subject: Re: *.dat file
From: Arlen -dot- P -dot- Walker -at- jci -dot- com
To: "TECHWR-L" <techwr-l -at- lists -dot- raycomm -dot- com>
Date: Thu, 18 Oct 2001 09:39:26 -0500

>I had a problem with *.dat files (a font that I asked someone to send me)
>and the person who sent them was using a PC but told me that the files had
>been created (?) on a MAC. So this may not be an e-mail problem, but a
>platform problem.

More likely a problem with a "helpful" mail handler. I've seen mail
handlers (not really servers, more like gateways which accept mail from one
mail system -- Notes, for example -- and "convert" it to another system
--SMTP, for example) which decide that *all* attachments *must* have a file
extension. Since file extensions are completely unnecessary on Macs (at
least until the Great Leap Backward in OSX) most files don't have one.
These "helpful" mail handlers therefore decide to add an extension to the
attachment, and it's usually ".dat," for reasons known only to the
developers of these abominations. A side effect of these "translations" is
that sometimes they render a binary file unusable by changing every
occurance of a return (byte value of 13) to linefeed (10) or
return+linefeed (13 followed by 10).

There is, BTW, an excellent usability reason using file extensions to
define the file type is a Bad Idea: Since one is allowed to change the file
name at will, one can change the file extension without affecting the
actual file format, and the results will mislead the user (intentionally or
unintentionally). One shouldn't be able to change the file type without
also changing the file contents.

As I noted to Jennifer, if you open those files with something that reads
text (such as WordPad) and they are truly Mac files, you'll see two groups
of four letters up near the front of the file which will identify the
application that created it and the file type. Apple no longer keeps an
authoritative list of file types, but you can search the registry of
creator codes here:

This should tell you what application created the file (unless the
developer never bothered to register the code; possible, but not likely for
commercial applications) and that should help you decide what the file type
is. (If you have a Mac and the application in question, it's fairly easy to
discover what the file type means, but we can assume that's not an option

Have fun,
Chief Managing Director In Charge, Department of Redundancy Department
DNRC 224

Arlen -dot- P -dot- Walker -at- JCI -dot- Com
In God we trust; all others must provide data.
Opinions expressed are mine and mine alone.
If JCI had an opinion on this, they'd hire someone else to deliver it.

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