Re: Chronological order of BSD, SV, and POSIX.1

[Alejandro Colomar <alx@kernel.org>]

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Hi Seth,

On Sat, Jan 17, 2026 at 10:37:36AM +0000, Seth McDonald wrote:
> Hi Alex,
> 
> In my next patch set (for system calls), I've generally been ordering
> POSIX.1-1988/1990 relative to BSD and SV according to their release
> years as specified in standards(7).  Which gives the following relative
> ordering between SV and POSIX.1:
> 
> SVr1
> SVr2
> SVr3
> 	POSIX.1-1988
> SVr4
> 	POSIX.1-1990
> SVID 4
> 
> And the following relative ordering between BSD and POSIX.1:
> 
> 3BSD
> 4BSD
> 4.1BSD
> 4.2BSD
> 4.3BSD
> 	POSIX.1-1988
> 	POSIX.1-1990
> 4.4BSD
> 
> Because many of the system calls I updated listed SVr4, and some listed
> 4.4BSD, I want to check that it makes sense to list them after
> POSIX.1-1988.  In case, for example, SVr4 is known to have influenced
> POSIX.1-1988 prior to being officially released.

Going back to this, yes, 4.4BSD seems clearly later than POSIX.1-1990.

SVr4 seems contemporaneous to POSIX.1-1988, so I don't mind whether we
put it before or after.  I think I'd put it before, because as you say,
it heavily influenced, even though formally POSIX.1-1988 seems to
derive from SVr3 (SVID Issue 2).  That also puts all SysV before all
POSIX, which seems cleaner.

Let's try to specify the order in the format you used above:

3BSD
4BSD
4.1BSD
	SysIII
	Unix/TS 4
4.2BSD
	SVr1
	SVr2
4.3BSD
	SVr3
	SVr4
					C89
		POSIX.1-1988
				XPG3
		POSIX.1-1990
				XPG4
				SUSv1
	SVID 4
4.4BSD
					C95
		POSIX.1-1996
				SUSv2
					C99
		POSIX.1-2001	SUSv3
		POSIX.1-2008	SUSv4
					C11
					C17
		POSIX.1-2024	SUSv5
					C23


Have a lovely day!
Alex

-- 
<https://www.alejandro-colomar.es>

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