Official Description UNC (Universal Naming Convention)

Question

Can anybody point to a man page or specification that defines the Universal Naming Convention (UNC)? I'm looking for the original source of the idea

"is often described as originating in Unix." - could you link to any such description? — Mat, Dec 03 '12 at 10:47
http://www.pcmag.com/encyclopedia_term/0,1237,t=UNC&i=53398,00.asp And yes, many people believe it's an MS invention. Memories differ, that's why I'm asking this question. — Isaac Rabinovitch, Dec 03 '12 at 18:27

Gilles 'SO- stop being evil' · Answer 1 · 2012-12-04T20:19:04.810

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The \\hostname\directory\… syntax does not (directly) originate in the Unix world, as far as I know. I do not know its origin; from what I can find on the web, UNC does not originate from Netware, nor does it come from Plan9 or VMS. By 1995, it was a native feature of both Windows NT and OS/2. OS/2 had the concept as far back as May 1993, which predates the first release of Windows NT. It may have originated from LAN Manager (developed wby Microsoft on top of IBM's OS/2, at a time when IBM and Microsoft were sharing OS/2 code).

An early mention of UNC is in US patent 5363487 (bottom of column 29, an fig. 9), filed in 1989 by Microsoft (thanks to John Summerfield for the reference). A later patent, US 5341499 (by IBM), affirms that “the Universal Naming Convention was jointly invented by IBM and Microsoft for use in their jointly developed Local Area Network (LAN) software products”. This is very likely to mean LAN Manager.

There is a smidgen of Unix inspiration in the UNC, in that it removes the need for drive letters, allowing network drives to be referenced directly instead of having to first assign a drive letter (and make sure not to have a conflict, with only 26 or 32 drive letters). But Unix used a more flexible mount point system from almost day 1, where a network drive can be attached at any point in the directory hierarchy and not at the top.

Unix acknowledges the UNC in that it allows // at the beginning of a path to be treated specially. From the POSIX rationale (A.4.11 Pathname Resolution):

Other networked systems use the construct //hostname for the same purpose.

Note that the rationale mentions “other systems”, not “historical usage”. This strongly implies that //hostname/directory is not historical usage in the Unix world, but usage in some other system where POSIX implementations might exist.

edited Dec 04 '12 at 20:19

answered Dec 03 '12 at 23:06

Gilles 'SO- stop being evil'

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Sigh. I think I need to rewrite the question so that folks will stop interpreting this as an invitation to argue about who invented UNC. I'm looking for information on the source of the idea. Thanks for the patent link, though. I disagree with your conclusions, but this is not the place to argue about that. – Isaac Rabinovitch Dec 04 '12 at 02:06
@IsaacRabinovitch The idea is closely tied with the notation. It's a product of the preexisting syntax for DOS paths (letter colon backslash directory backslash file) modified to accommodate remote paths in a simple way (simpler than the Unix syntax which is more general (so less easy to parse) and requires mounting before use — a problem which the Unix world solved through automounting). – Gilles 'SO- stop being evil' Dec 04 '12 at 08:46
Nice theory. But I'm looking for documents. – Isaac Rabinovitch Dec 04 '12 at 20:07
@IsaacRabinovitch I found an explicit acknowledgement in another patent. It is from LAN Manager (at least in its precise form of double-directory-separator, hostname, absolute-remote-path). – Gilles 'SO- stop being evil' Dec 04 '12 at 20:20
Yep, sort of thing I'm looking for. Patent #? – Isaac Rabinovitch Dec 05 '12 at 04:06
@IsaacRabinovitch I updated my answer. – Gilles 'SO- stop being evil' Dec 05 '12 at 11:03
The patent uses UNC as a convenient shorthand for the notation. Nowhere does it reference a document that defines UNC. – Isaac Rabinovitch Dec 05 '12 at 20:29
@IsaacRabinovitch I invite you to read this question. And, there is a reference to a manual of Apollo Domain/OS from(First Printing: July, 1985) that already had implemented // as network root, as opposed to / for local root. By the rule of "Prior Art" the patent of 1989 should not have been granted. – Jan 22 '16 at 03:36

score 6 · Answer 2 · answered Sep 11 '13 at 16:24

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Extending local file systems to be part of a larger network via '//hostname/directory/filename' notation dates back to at least Apollo/DomainOS (1981), though it wasn't called UNC at the time. Apollo/DomainOS could be used with SysV and BSD Unix environments.

See chapter 1 in http://www.typewritten.org/Articles/Apollo/005488-02.pdf

answered Sep 11 '13 at 16:24

Karsten Blees

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+1 The Newcastle Connection (on top of Unix v7) might have predated that (using /../host/path instead of //host/path though). – Stéphane Chazelas Jan 22 '16 at 17:10

bahamat · Answer 3 · 2012-12-03T20:16:59.180

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As I remember it (and Wikipedia concurs), UNC is a term that originates from Microsoft Windows.

In fact, I don't think I've ever heard before that it originated in UNIX.

Furthermore, I can't find any references to UNC in either POSIX or any RFC. Every reference I have found elsewhere is in relation to Windows. And the singular reference you cite referring to UNIX as the origin also cites Windows as the origin.

There's a game they play on Sesame Street...

One of these things is not like the others...

This lack of reference is the best evidence I can find that leads to the conclusion that the term did not originate in UNIX. Granted, absence of evidence is not evidence of absence. But it seems more probable that there's an error in PC Mag's definition than that there's a gaping omission in the POSIX specification and that in all this time there was never an RFC defining UNC, much less even mentioning it.

But I'll gladly down vote my own post if I'm wrong.

edited Dec 03 '12 at 20:16

answered Dec 03 '12 at 08:28

bahamat

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I've expanded my answer with respect to the POSIX specification and RFC's. Granted, absence of evidence is not evidence of absence. However it does heavily weigh the probability factor. – bahamat Dec 03 '12 at 19:59
I'd say the exact opposite. There is no evidence that stars guide our destiny. There's more evidence to the contrary. If the evidence contradicts your belief then it's time to change your belief. – bahamat Dec 03 '12 at 20:04
And W3C can't decide for URL or URI either. – bahamat Dec 03 '12 at 20:06
let us continue this discussion in chat – bahamat Dec 03 '12 at 20:08
No, I'm saying that lack of reference in either POSIX or any RFC is evidence that the term is unlikely to have originated with UNIX. – bahamat Dec 03 '12 at 20:09
The argument formerly here has been moved to chat. I'm going to just say that I don't want to prove bahamat wrong, I just want evidence that's harder than what I've been able to find through googling and wikipeda. – Isaac Rabinovitch Dec 03 '12 at 20:16
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Actually, there is a mention in the POSIX rationale (not by name), which strongly suggests a non-Unix origin. – Gilles 'SO- stop being evil' Dec 03 '12 at 23:07
And that (not by name) is why I didn't find it. – bahamat Dec 05 '12 at 19:19

Official Description UNC (Universal Naming Convention)

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