If you like playing with beta versions of Windows, you'll have seen that strange looking version number. If you've asked yourself what it means, here it is.
Here's an example build tag: 6.2.8102.101.x86fre.winmain_win8m3.110830-1739.92eb4451821f0730
So let's break the full tag into several smaller parts.
NT Major Version
NT Minor Version
CPU Architecture/Build Type
Time of compilation
Rights Account Certificate GUID1
1: Present only in Windows 8 M2 builds and up
NT Major Version: This is the first section of the build tag. In this case, it's 6, showing that that the code is NT Version 6. It's changed when major overhauls of the NT code have been done.
NT Minor Version: This is the second section of the build tag. In this case, it's 2, showing that this is the second minor release of NT Version 6.
Build number: This is the third section of the build tag and in most cases, where Winver stops (for example, Version 6.2 (Build 7955)). The build number shows how many times the NT code has been compiled since 1988 or so.
Revision/Delta: It shows how many times little tweaks and bugfixes have been made. These changes aren't significant enough to warrant a full recompile of the code, but they are still recorded. Inside Microsoft, this section is known as the Delta.2 2: Thanks to Daniel for this information
CPU Architecture/Build Type: What type of CPU the build was compiled for. A few different ones exist, including x86 and AMD64. The Build Type is how it was designed to be used. There are two different Build Types: Checked and Free. The Free build is probably what you're on right now. All code optimizations are present and if a critical error occurs, the OS traps it. The Checked build lacks these optimizations however and is much slower than the Free build. It also depends on a debugger to be attached for when a critical error occurs.
Build lab: Inside Microsoft, there are many different groups working on the NT source code. Things would get pretty confusing if this section didn't exist, so each group (called a lab) has its own name. For example: winmain means the code was compiled in the Windows Main build lab. winmain is where all the code from all the other build labs gets stitched together for the next winmain release. Sometimes winmain may be followed by _win(version)mX; this is the Milestone part of the tag. Milestones are goals the Windows developers are working to. This Milestone part of the tag might be seen as winmain_win8m3. Other build labs that are commonly seen are the FBLs, or Feature Build Labs. They write the code to all the fun stuff in Windows.
Compilation date: This is the date this build was compiled. It's read as YY/MM/DD. A build tag with 110228 as the compilation date would mean the build was compiled on February 28th, 2011.
Time of compilation: The last part of the build tag.3 It's in 24-hour format, so 1930 would be read as 19:30 or 7:30 PM. 3: Only the last part of the build tag in Windows builds prior to Windows 8 M2
Rights Account Certificate GUID: This part of the tag is present in Windows 8 M2 and up. It's used to enable locked features on a per-employee basis and is unique for every key provided and for every build compiled., making it easy to trace the build unless the default product key has been used. It is tied to several licensing system components and the hash is generated by an algorithm that is made by several objects within the core Windows files.4 4: Thanks to arseny92 for explaining how this works and what its name is.
Review: The build tag 6.2.8102.101.x86fre.winmain_win8m3.110830-1739.92eb4451821f0730 means this when broken down:
6 <-- Major version of Windows 2 <-- Minor version of Windows 101 <-- Revision x86fre <-- CPU Arch. and Build Type winmain_win8m3 <-- Build lab 110830 <-- Compilation Date in YY/MM/DD 1739 <-- Time of compilation 92eb4451821f0730 <-- Rights Account Certificate GUID (Win8 M2 and up only)
Last edited by linuxlove on Sun Jun 26, 2011 2:49 pm, edited 5 times in total.
Post subject: Re: Dissecting a Windows build tag Posted: Mon Apr 11, 2011 4:29 pm
Joined Thu Oct 23, 2008 3:25 am
Favourite OS Real Life
If not, very close to that many.
There was some discussion that Windows build's numeration isn't continuous but discrete.
It's known that they decided to jump builds for public release, but what isn't known is whether or not they still keep compiling behind the scenes after RTM to see what else they can do to their code. Post-RTM compiles are known to exist of 7, with build tags of around the 77xx range.
Post subject: Re: Dissecting a Windows build tag Posted: Tue Apr 12, 2011 8:59 pm
Newbie Beta Collector
Joined Tue Apr 12, 2011 5:35 pm
Are you sure that 7599 builds were compiled before Windows 7 RTM?
If not, very close to that many.
Sorry, I need to step in here. The 74xx and 75xx were built after RTM. A 72xx/73xx build became RTM. With the Win7 branch, there was alot of sub-branches and they made several post-RTM builds that were not built around SP1
Post subject: Re: Dissecting a Windows build tag Posted: Sat Apr 16, 2011 11:39 am
Amateur Beta Collector
Joined Thu Sep 23, 2010 8:14 am
Favourite OS NT 6.3
About the Build Number, I think that MS changes the build number only for a major release, and it actually counts how many times that major build was recompiled.
For example: - Windows Vista went up to 6.0.6000 when the RTM was released and for SP 1 & 2 they only changed the last number of the build 600x . - Windows 7 continued from the Vista build number and went even higher to version 6.1.7600 , as for Win 7 SP1 goes the same rule as for Vista SP's - Now for the next Windows release , it started based on some POST-RTM releases of Win 7 (77xx) with some modification in M1 (6.1.7850) after wich the minor version was changed from 1 to 2 bringing the latest Mileston (3) to somewhere around 6.2.79xx.