Question: .spv file extension

Hello gang. how's everyone today ?
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Here's my problem I went to ftp.microsoft.com and pulled down the fullkb (and doesnt that take an hour out of your life.and that's with a cable modem getting 70kb/s) and they of course come as zip files. got the trusty winzip out and started going crazy unzipping. but the extension on these files after extracting is .spv that's a new one for me, am unfamiliar with that extension. I am sure it is probably a common one and I have probably seen it a million times and just never paid attention, but look at it this way. You get to tell me how stupid I am for not recognizing it, and that is an opportunity not to be missed.

thanks gang
mike