In the comments at https://www.askwoody.com/forums/topic/confusion-in-the-group-a-ranks/ there is a discussion about whether there are different types of supersedence that apply to Windows updates. I have more insights now that I’d like to share.
Let’s first discuss how the list of updates that Windows Update shows is generated. When you use Windows Update to check for Windows updates in Windows 7 (and I assume also in Windows 8.1), the following seems to happen (simplified version):
1. The Windows Update client gets a list of all applicable updates that are not installed on your computer.
2. Any updates in the list in step 1 that you had previously marked as hidden are removed from the list.
3. Any updates in the list in step 2 that Microsoft considers to be superseded by any other updates in the list in step 2 are removed from the list.
The first type of supersedence seems to relate to the above process of which applicable but not yet installed updates are shown to the user in Windows Update. This type of supersedence is declared by Microsoft and is listed in the Package Details tab of a given update at Microsoft Update Catalog; example: https://www.catalog.update.microsoft.com/ScopedViewInline.aspx?updateid=270cb4c4-685a-4bf2-bd53-9c314d6ffc47. An important detail is that a given update might contain a newer version of all the components in another update, but Microsoft might purposely not consider the newer update to supersede (in this first type of supersedence) the older update. Let’s consider why with an example. The Windows 7 September 2016 Optional rollup update KB3185278 contains (among other things) a non-security update to Windows Media Player that updates Windows Media Player to v12.0.7601.23517. Windows 7 March 2016 security update KB3138962 contains an older version of Windows Media Player, v12.0.7601.19148. Yet the supersedence metadata for KB3138962 doesn’t list KB3185278 as superseding KB3138962, and there is a very good reason for this; if KB3185278 was considered by Microsoft as superseding KB3138962, then if both of those updates were not installed on your computer, security update KB3138962 would not be shown in Windows Update due to the presence of optional update KB3185278 in the Windows Update list, which would be a very undesirable result.
There seems to be a second meaning of supersedence involving components of an update that is distinctly different than the first meaning of supersedence and doesn’t seem to use the supersedence metadata mentioned in the first meaning. A usage of this second meaning: When trying to install a given update, it can be considered superseded because its components are superseded by components already on the computer. Another usage of this second meaning: From Disk Cleanup Wizard addon lets users delete outdated Windows updates on Windows 7 SP1 or Windows Server 2008 R2 SP1: “Therefore, after you run the Disk Cleanup wizard, you may be unable to roll back to a superseded update. If you want to roll back to a superseded update that the Disk Cleanup wizard deletes, you can manually install the update.”
I’ll leave you with a question for discussion that you may now be in a position to answer. According to the Windows 7 supersedence metadata for Internet Explorer cumulative update KB4036586, KB4036586 supersedes Internet Explorer cumulative update KB3185319. But yet on a Windows 7 computer with neither of these updates installed, after installing KB4036586 and then checking for updates with Windows Update, KB3185319 was listed as available, and manually installing KB3185319 did not give the message “The update is not applicable to your computer.” My question to you is: How is this possible?
