Groups > alt.folklore.computers > #235372

Re: Origin Of Filename Extension Dot Separator

From	Snidely <snidely.too@gmail.com>
Newsgroups	alt.folklore.computers, alt.english.usage, alt.usage.english
Subject	Re: Origin Of Filename Extension Dot Separator
Date	2026-08-25 11:22 -0700
Organization	Dis One
Message-ID	<mn.caaa7ea8c65fe2b1.127094@snitoo> (permalink)
References	<v8p8g6$ai44$1@dont-email.me> <116hu7n$32c3b$2@toylet.eternal-september.org> <%X0jS.2$XsQ3.0@fx01.ams4> <116j56b$3eghm$1@toylet.eternal-september.org> <116kcln$1s91$1@gal.iecc.com>

Cross-posted to 3 groups.

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John Levine  scribbled something on Tuesday the 8/25/2026:
> According to Mr. Chang Man-wai <toylet.toylet@gmail.com>:

(crossposting put on a diet)

>> But in the naming method,
>> which is the file name?
>> Which is the file name extension? :)

By convention, a computer filename is the whole string identifying the 
file, but can also be used to describe the substring that is everything 
up to the extension (and its separator).  The extension is everything 
after the last separator.  In MSDOS days ... and other simple file 
systems,  like the CP/M ancestor of FAT ... the extension was the 3 
characters that fit into the directory entry structure field labeled 
"extension".

>
> I think the question doesn't make sense. The reason computer files have
> extensions is to describe the format of the contents: text, executables,
> spreadsheet, whatever. That makes it a lot easier to select the appropriate
> software to process them. Microsoft famously got this wrong, by looking at 
> the contents of the file to decide how to process it instead of the name, so 
> you can have a mail attachment called CONTRACT.TXT which is in fact an 
> executable full of malware.

I don't think this is what Microsoft did.  Unix is the OS that uses 
"magic" (special bytes at offset 0) to decode what a file is ... you 
can specify which shell is to execute a script, for instance.  (Linux 
has also adpted this technique.)

Microsoft is famous for trying to open a binary file in a text editor 
because it has a .txt extension.

> In paper files, it's generally obvious what kind of material is in the
> folder, or if it's not, it doesn't matter since there's only one way to
> process it, pull out the file and look at it.

There are plenty of situations where a librarian is dependent on a 
subject matter expert to identify what a book or paper file is.  And 
they may need help to identiify which expert is needed.

/dps

-- 
Trust, but verify.

Thread

Re: Origin Of Filename Extension Dot Separator anthk@not.dev.null - 2026-08-17 23:57 +0200
  Re: Origin Of Filename Extension Dot Separator John Levine <johnl@taugh.com> - 2026-08-18 00:07 +0000
    Re: Origin Of Filename Extension Dot Separator Bob Eager <throwaway0008@eager.cx> - 2026-08-18 11:51 +0000
      Re: Origin Of Filename Extension Dot Separator Rich Alderson <news@alderson.users.panix.com> - 2026-08-18 22:15 -0400
    Re: Origin Of Filename Extension Dot Separator Rich Alderson <news@alderson.users.panix.com> - 2026-08-18 22:13 -0400
  Re: Origin Of Filename Extension Dot Separator Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-23 07:32 +0000
    Re: Origin Of Filename Extension Dot Separator Peter Flass <Peter@Iron-Spring.com> - 2026-08-23 07:40 -0700
      Re: Origin Of Filename Extension Dot Separator Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-23 22:07 +0000
        Re: Origin Of Filename Extension Dot Separator Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-24 07:27 +0800
          Re: Origin Of Filename Extension Dot Separator vallor <vallor@vallor.earth> - 2026-08-24 01:31 +0000
            Re: Origin Of Filename Extension Dot Separator Chris Ahlstrom <OFeem1987@teleworm.us> - 2026-08-25 15:02 -0400
    Re: Origin Of Filename Extension Dot Separator Rich Alderson <news@alderson.users.panix.com> - 2026-08-23 23:36 -0400
  Re: Origin Of Filename Extension Dot Separator "Mr. Chang Man-wai" <toylet.toylet@gmail.com> - 2026-08-23 23:13 +0800
    Re: Origin Of Filename Extension Dot Separator Lars Poulsen <lars@beagle-ears.com> - 2026-08-23 11:20 -0700
      Re: Origin Of Filename Extension Dot Separator Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-23 22:11 +0000
        Re: Origin Of Filename Extension Dot Separator Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-24 07:28 +0800
        Re: Origin Of Filename Extension Dot Separator Rich Alderson <news@alderson.users.panix.com> - 2026-08-23 23:39 -0400
      Re: Origin Of Filename Extension Dot Separator "Mr. Chang Man-wai" <toylet.toylet@gmail.com> - 2026-08-25 01:15 +0800
        Re: Origin Of Filename Extension Dot Separator Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-25 03:28 +0800
          Re: Origin Of Filename Extension Dot Separator "Mr. Chang Man-wai" <toylet.toylet@gmail.com> - 2026-08-25 12:20 +0800
            Re: Origin Of Filename Extension Dot Separator John Levine <johnl@taugh.com> - 2026-08-25 15:34 +0000
              Re: Origin Of Filename Extension Dot Separator John Ames <commodorejohn@gmail.com> - 2026-08-25 09:35 -0700
                Re: Origin Of Filename Extension Dot Separator scott@slp53.sl.home (Scott Lurndal) - 2026-08-25 17:00 +0000
                Re: Origin Of Filename Extension Dot Separator "Mr. Chang Man-wai" <toylet.toylet@gmail.com> - 2026-08-28 20:07 +0800
                Re: Origin Of Filename Extension Dot Separator Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-29 16:59 +0800
                Re: Origin Of Filename Extension Dot Separator "Mr. Chang Man-wai" <toylet.toylet@gmail.com> - 2026-08-30 04:13 +0800
              Re: Origin Of Filename Extension Dot Separator Snidely <snidely.too@gmail.com> - 2026-08-25 11:22 -0700
                Re: Origin Of Filename Extension Dot Separator Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-25 21:43 +0000
                Re: Origin Of Filename Extension Dot Separator scott@slp53.sl.home (Scott Lurndal) - 2026-08-26 15:34 +0000
                Re: Origin Of Filename Extension Dot Separator Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-29 17:08 +0800
              Re: Origin Of Filename Extension Dot Separator "Mr. Chang Man-wai" <toylet.toylet@gmail.com> - 2026-08-28 20:12 +0800
                Re: Origin Of Filename Extension Dot Separator John Levine <johnl@taugh.com> - 2026-08-28 18:14 +0000
                Re: Origin Of Filename Extension Dot Separator Rich Alderson <news@alderson.users.panix.com> - 2026-08-28 21:02 -0400
                Re: Origin Of Filename ... text and civilization? doomsday? "Mr. Chang Man-wai" <toylet.toylet@gmail.com> - 2026-08-29 10:15 +0800
                Re: Origin Of Filename ... text and civilization? doomsday? "Mr. Chang Man-wai" <toylet.toylet@gmail.com> - 2026-08-29 11:55 +0800
                Re: Origin Of Filename ... text and civilization? doomsday? Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-29 17:38 +0800
                Re: Origin Of Filename ... text and civilization? doomsday? "Mr. Chang Man-wai" <toylet.toylet@gmail.com> - 2026-08-30 04:09 +0800
                Re: Origin Of Filename ... text and civilization? doomsday? Rich Alderson <news@alderson.users.panix.com> - 2026-08-29 18:31 -0400
                Re: Origin Of Filename ... text and civilization? doomsday? Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-30 11:33 +0800
                Re: Origin Of Filename ... text and civilization? doomsday? John Ames <commodorejohn@gmail.com> - 2026-08-31 09:34 -0700
                Re: Origin Of Filename ... text and civilization? doomsday? "Mr. Chang Man-wai" <toylet.toylet@gmail.com> - 2026-09-02 22:59 +0800
                Re: Origin Of Filename ... text and civilization? doomsday? John Ames <commodorejohn@gmail.com> - 2026-09-02 08:29 -0700
                Re: Origin Of Filename ... text and civilization? doomsday? Peter Flass <Peter@Iron-Spring.com> - 2026-09-02 12:36 -0700
                Re: Origin Of Filename ... text and civilization? doomsday? John Ames <commodorejohn@gmail.com> - 2026-09-02 13:00 -0700
                Re: Origin Of Filename ... Babylon cuneiforms etched on bread? Exorcism? "Mr. Chang Man-wai" <toylet.toylet@gmail.com> - 2026-09-04 12:24 +0800
                Re: Origin Of Filename ... text and civilization? doomsday? Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-02 21:55 +0000
                Re: Origin Of Filename ... text and civilization? doomsday? James Dow Allen <user4353@newsgrouper.org.invalid> - 2026-09-03 04:44 +0000
                Re: Origin Of Filename ... text and civilization? doomsday? Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-03 04:57 +0000
                Re: Origin Of Filename ... text and civilization? doomsday? James Dow Allen <user4353@newsgrouper.org.invalid> - 2026-09-03 05:29 +0000
                Re: Origin Of Filename ... text and civilization? doomsday? Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-03 06:57 +0000
                Re: Origin Of Filename ... text and civilization? doomsday? James Dow Allen <user4353@newsgrouper.org.invalid> - 2026-09-03 10:06 +0000
                The Amarna Letters, Hebrew -- wait, which brew? (was: Re: Origin Of Filename ... text and civilization? doomsday?) Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-09-03 18:29 +0800
                Re: The Amarna Letters, Hebrew -- wait, which brew? (was: Re: Origin Of Filename ... text and civilization? doomsday?) John Ames <commodorejohn@gmail.com> - 2026-09-03 08:02 -0700
                Re: The Amarna Letters, Hebrew -- wait, which brew? (was: Re: Origin Of Filename ... text and civilization? doomsday?) athel.cb@gmail.com <user12588@newsgrouper.org.invalid> - 2026-09-03 15:49 +0000
                Re: The Amarna Letters, Hebrew -- wait, which brew? (was: Re: Origin Of Filename ... text and civilization? doomsday?) Tony Cooper <tonycooper214@gmail.com> - 2026-09-03 14:08 -0400
                Re: The Amarna Letters, Hebrew -- wait, which brew? (was: Re: Origin Of Filename ... text and civilization? doomsday?) John Ames <commodorejohn@gmail.com> - 2026-09-03 11:34 -0700
                Re: The Amarna Letters, Hebrew -- wait, which brew? (was: Re: Origin Of Filename ... text and civilization? doomsday?) Tony Cooper <tonycooper214@gmail.com> - 2026-09-03 18:01 -0400
                Re: The Amarna Letters, Hebrew -- wait, which brew? Peter Flass <Peter@Iron-Spring.com> - 2026-09-03 15:26 -0700
                Re: The Amarna Letters, Hebrew -- wait, which brew? (was: Re: Origin Of Filename ... text and civilization? doomsday?) Steve Hayes <hayesstw@telkomsa.net> - 2026-09-04 04:51 +0200
                Re: The Amarna Letters, Hebrew -- wait, which brew? (was: Re: Origin Of Filename ... text and civilization? doomsday?) James Dow Allen <user4353@newsgrouper.org.invalid> - 2026-09-04 04:27 +0000
                Re: The Amarna Letters, Hebrew -- wait, which brew? Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-09-04 12:52 +0800
                Re: The Amarna Letters, Hebrew -- wait, which brew? John Ames <commodorejohn@gmail.com> - 2026-09-04 08:15 -0700
                Re: The Amarna Letters, Hebrew -- wait, which brew? (was: Re: Origin Of Filename ... text and civilization? doomsday?) Steve Hayes <hayesstw@telkomsa.net> - 2026-09-05 06:05 +0200
                Re: The Amarna Letters, Hebrew -- wait, which brew? (was: Re: Origin Of Filename ... text and civilization? doomsday?) James Dow Allen <user4353@newsgrouper.org.invalid> - 2026-09-05 09:13 +0000
                Re: Origin Of Filename ... text and civilization? doomsday? Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-05 21:09 +0000
                Re: The Amarna Letters, Hebrew -- wait, which brew? Malcolm Purvis <malcolm@purvis.id.au> - 2026-09-04 06:49 +1000
                Re: The Amarna Letters, Hebrew -- wait, which brew? Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-03 21:27 +0000
                Re: Origin Of Filename ... text and civilization? doomsday? Peter Flass <Peter@Iron-Spring.com> - 2026-09-03 08:28 -0700
                Re: Origin Of Filename ... text and civilization? doomsday? Rich Alderson <news@alderson.users.panix.com> - 2026-09-02 15:37 -0400
                Re: Origin Of Filename ... text and civilization? doomsday? Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2026-08-29 05:25 +0000
                Re: Origin Of Filename ... text and civilization? doomsday? "Mr. Chang Man-wai" <toylet.toylet@gmail.com> - 2026-08-29 13:35 +0800
                Re: Origin Of Filename ... text and civilization? doomsday? Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2026-08-29 17:35 +0000
                Re: Origin Of Filename ... text and civilization? doomsday? Chris Ahlstrom <OFeem1987@teleworm.us> - 2026-08-29 15:42 -0400
                Re: Origin Of Filename ... text and civilization? doomsday? Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2026-08-29 21:07 +0000
                Re: Origin Of .... "say what?" "Mr. Chang Man-wai" <toylet.toylet@gmail.com> - 2026-08-30 18:00 +0800
                Re: Origin Of Filename ... text and civilization? doomsday? "Mr. Chang Man-wai" <toylet.toylet@gmail.com> - 2026-08-30 04:17 +0800
                Re: Origin Of Filename Extension Dot Separator Charles Hope <clh@candehope.me.uk> - 2026-08-29 09:45 +0000
                Re: Origin Of Filename Extension Dot Separator Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-29 17:14 +0800
                Re: Origin Of Filename Extension Dot Separator "Mr. Chang Man-wai" <toylet.toylet@gmail.com> - 2026-08-30 03:52 +0800
                Re: Origin Of ..... Darklands the video game? Medieval Europe? "Mr. Chang Man-wai" <toylet.toylet@gmail.com> - 2026-08-30 04:24 +0800
                Re: Origin Of ..... Darklands & the Holy Roman Empire? 15th century?? "Mr. Chang Man-wai" <toylet.toylet@gmail.com> - 2026-08-30 16:47 +0800
                Re: Origin Of ..... Darklands the video game? Medieval Europe? Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-08-31 17:08 +0800
                Re: Origin Of ..... Darklands the video game? Medieval Europe? "Kerr-Mudd, John" <admin@127.0.0.1> - 2026-08-31 16:40 +0100
                Re: Origin Of ..... Darklands the video game? Medieval Europe? Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-09-03 00:06 +0800
                Re: Origin Of ..... Darklands the video game? Medieval Europe? "Mr. Chang Man-wai" <toylet.toylet@gmail.com> - 2026-09-02 23:02 +0800
             Tops-10 filename/extension representation [was Re: Origin Of Filename Extension Dot Separator] Rich Alderson <news@alderson.users.panix.com> - 2026-08-25 16:15 -0400
              Re: Tops-10 filename/extension representation [was Re: Origin Of Filename Extension Dot Separator] Kragen Javier Sitaker <kragen@canonical.org> - 2026-09-05 10:14 -0300
                Re: Tops-10 filename/extension representation [was Re: Origin Of Filename Extension Dot Separator] Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-09-05 21:11 +0000

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