The following are two example filenames from the %WINDIR%\WinSxS\Manifests directory:


The scheme is obvious except for the last element: processorArchitecture_AssemblyName_publicKeyToken_Version_Language_UNKNOWN.manifest

What is the meaning of the last 16 hexadecimal characters in the WinSxS\Manifests files' names?

Current research effort:

  • I can rule out that the characters represent the hexadecimal encoded low- and high-order parts of a FILETIME structure since the resulting time stamps are astronomically large.
  • These strings are not found in the registry
  • It is not a CRC-64 checksum of the manifest file itself
  • These strings are already present in the downloads from Microsoft (I've unpacked a .cab file embedded in a windows update .mum file)
  • 1
    Not the downvoter, but you might want to provide more information on what you're trying to do with this. I agree that the downvote should have been accompanied by some explanation of the issue.
    – bwDraco
    Mar 11, 2016 at 0:49
  • It's probably just a unique ID. I doubt there's any significant meaning other than to distinguish it from identical files which differ only in version. Mar 11, 2016 at 1:55
  • allquixotic may be right. I also wonder if this is some sort of standard that StackOverflow users might be more familiar with.
    – TOOGAM
    Mar 11, 2016 at 17:49
  • @TOOGAM I guess so, although this cleary is not a programming question.
    – gollum
    Mar 11, 2016 at 17:58
  • 1
    @gollum Agreed. Yet that is where there is a talent base of more people who may know the correct answer. You might need to get borderline infringing in a new question, like "does this WinSxS filename match a known standard that identifies the UNKNOWN segment? (P.S. What I'm really looking for are details of the UNKNOWN segment.)" I agree this question won't be right up their alley, so it may not be highly rated, but some knowledgeable expert may have pity if your question seems intelligent enough. Many of us are, after all, here to help.
    – TOOGAM
    Mar 11, 2016 at 18:01


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