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== Textual representation ==
== When Microsoft started using UUIDs ==
Move this section up before the Variants and special cases section [[User:Theking2|Theking2]] ([[User talk:Theking2|talk]]) 13:17, 2 March 2024 (UTC)


== What are the different variants of Version 4 UUID's used for? ==
To help fill in the history for when Microsoft started using UUIDs (the "when" question is flagged in the article), I have a bit of information that might help someone search for the answer.


From what I can determine, Version 4 UUID's -- the random kind -- have four variants, signified by the 17th hex digit being one of "8", "9", " a", or "b" (which is how I will refer to each variant here).
I attended a Microsoft conference at the Redmond campus in 1995 where a presenter gave information about UUIDs, how they are essentially unique, and that Microsoft was going to be using them.


What are these four different variants <i><b>for</b></i>? How are they <i><b>used</b></i>? What determines the use of (say) variant "a" rather than variant "8"?
That's not enough to put into the article, obviously, but maybe it'll help give a timeline if someone is researching this. <!-- Template:Unsigned --><span class="autosigned" style="font-size:85%;">—&nbsp;Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[User:Chris uvic|Chris uvic]] ([[User talk:Chris uvic#top|talk]] • [[Special:Contributions/Chris uvic|contribs]]) 18:20, 30 June 2021 (UTC)</span> <!--Autosigned by SineBot-->


I'm writing a program to generate these UUID's pseudorandomly, and I don't want to make some kind of ghastly error by providing the wrong type of UUID! Is there a reason why one would use one v4 variant and not another? Are some v4 variants more apprpriate for some uses, and others for other uses? The ONLY document I've yet come across that addresses this issue says (in relevant part):
== Other vairants of UUID ==


<blockquote><i>"...Version-4, variant-1 UUIDs are used in the game Minecraft... Version-4, variant-2 is called a "GUID" on Microsoft systems..."</i>
Reviewing logs in a web gateway, UUID Variant "e" was observed in the wild. This is not Random as fields 3 4 5 are the same between two seperate UUIDs


(Source: https://www.uuidtools.com/uuid-versions-explained, Retrieved: Fri., 30-Sep-2022 at 08:43:17pm -0400 UTC.)</blockquote>
406bb3ab-a127-ec11-981f-c896653b5010
213d5787-2629-ec11-981f-c896653b5010


However, this leaves unanswered qustions. First (and most obvious) is, what about variants 3 and 4 (what I call "a" and "b" above)?
https://email.ngpvan.com/unsubscribeUnique/406bb3ab-a127-ec11-981f-c896653b5010/213d5787-2629-ec11-981f-c896653b5010?nvep=ewogICJUZW5hbnRVcmkiOiAibmdwdmFuOi8vdmFuL05HUC9OR1A0Mi8xLzg4NTAzIiwKICAiRGlzdHJpYnV0aW9uVW5pcXVlSWQiOiAiMjEzZDU3ODctMjYyOS1lYzExLTk4MWYtYzg5NjY1M2I5MjA4IiwKICAiRW1haWxBZGRyZXNzIjogImxvbGVyY29hc3RlckBjaXNjby5jb20iCn0%3D
&hmac=wVRUIC0pn7S85lof8rzhxr1gJh2MXaBVOMZRmH_96HI=&id=1326529531


Also, the phrases "are used in" and "is called a" don't tell me whether these variants are <i>exclusively reserved</i> for these uses, or if it is permitted to use them for other, additional, purposes as well.
*Log has been altered to remove PII while not changing data type/or meaning


The main Wikipedia article doesn't even remotely <i><b>begin</b></i> to even <i><b>touch</b></i> upon this question...
[[Special:Contributions/173.38.117.90|173.38.117.90]] ([[User talk:173.38.117.90|talk]])DBNerd <!--Template:Undated--><small class="autosigned">—&nbsp;Preceding [[Wikipedia:Signatures|undated]] comment added 13:13, 11 October 2021 (UTC)</small> <!--Autosigned by SineBot-->


Guidance? Help? Please?
== New Versions ==


== Citation needed ==
There is a draft RFC which introduces versions 6, 7 and 8, as well as a form called MAX UUID.


The text says a citation for DomainOS is needed. Here are two:
https://datatracker.ietf.org/doc/html/draft-peabody-dispatch-new-uuid-format#section-3


Leach, P. J., Levine, P.H., Hamilton, J. A., Stumpf, B.L.,
I don't know if this proposal merits inclusion, or if we should wait until it is finalized.
"UIDs as Internal Names in a Distributed File System,"
in Proceedings ACM SIGACT-SIGOPS Symposium on Principles of Distributed Computing,
Ottawa, Ont., Aug. 18-20, 1982, pp. 34-41.


Leach, P. J., Levine, P.H., Douros, B. D., Hamilton, J. A., Nelson, D. L., Stumpf, B.L.,
[[User:Bend1010|Bend1010]] ([[User talk:Bend1010|talk]]) 20:31, 20 July 2022 (UTC)
"The Architecture of an Integrated Local Network,"
IEEE Journal on Selected Areas in Communications,
v.SAC-1, n.5, Nov. 1983, pp. 842-857.

The first is more about UIDs in DomainOS, the second is about the OS overall. [[User:Paul Jay Seattle|Paul Jay Seattle]] ([[User talk:Paul Jay Seattle|talk]]) 23:18, 15 September 2023 (UTC)

Latest revision as of 14:11, 10 July 2024

Textual representation

[edit]

Move this section up before the Variants and special cases section Theking2 (talk) 13:17, 2 March 2024 (UTC)[reply]

What are the different variants of Version 4 UUID's used for?

[edit]

From what I can determine, Version 4 UUID's -- the random kind -- have four variants, signified by the 17th hex digit being one of "8", "9", " a", or "b" (which is how I will refer to each variant here).

What are these four different variants for? How are they used? What determines the use of (say) variant "a" rather than variant "8"?

I'm writing a program to generate these UUID's pseudorandomly, and I don't want to make some kind of ghastly error by providing the wrong type of UUID! Is there a reason why one would use one v4 variant and not another? Are some v4 variants more apprpriate for some uses, and others for other uses? The ONLY document I've yet come across that addresses this issue says (in relevant part):

"...Version-4, variant-1 UUIDs are used in the game Minecraft... Version-4, variant-2 is called a "GUID" on Microsoft systems..." (Source: https://www.uuidtools.com/uuid-versions-explained, Retrieved: Fri., 30-Sep-2022 at 08:43:17pm -0400 UTC.)

However, this leaves unanswered qustions. First (and most obvious) is, what about variants 3 and 4 (what I call "a" and "b" above)?

Also, the phrases "are used in" and "is called a" don't tell me whether these variants are exclusively reserved for these uses, or if it is permitted to use them for other, additional, purposes as well.

The main Wikipedia article doesn't even remotely begin to even touch upon this question...

Guidance? Help? Please?

Citation needed

[edit]

The text says a citation for DomainOS is needed. Here are two:

Leach, P. J., Levine, P.H., Hamilton, J. A., Stumpf, B.L., "UIDs as Internal Names in a Distributed File System," in Proceedings ACM SIGACT-SIGOPS Symposium on Principles of Distributed Computing, Ottawa, Ont., Aug. 18-20, 1982, pp. 34-41.

Leach, P. J., Levine, P.H., Douros, B. D., Hamilton, J. A., Nelson, D. L., Stumpf, B.L., "The Architecture of an Integrated Local Network," IEEE Journal on Selected Areas in Communications, v.SAC-1, n.5, Nov. 1983, pp. 842-857.

The first is more about UIDs in DomainOS, the second is about the OS overall. Paul Jay Seattle (talk) 23:18, 15 September 2023 (UTC)[reply]

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