What is Vista Ultimate TECH SKU?

I know the features of the various Vista options (Business, Premium, Ultimate etc.), But NewEgg has some that I don't understand. There is Vista Ultimate upgrade (normal and signature). There is the Premium and Ultimate "TECH SKU" versions which cost more money. I have tried to find out what the "TECH SKU" versions are from NewEgg, but I haven't heard from them. There is no explanatiion on their Web site that I can find. Does anyone know what the TECH SKU version means--or the difference between the Ultimate and the Ultimate signature? Thank you for any help and info you can provide!

Thank you---I thought that might be what it meant. Here is the item from NewEgg that dcosts $327.99---
Microsoft Windows Vista Ultimate Upgrade Tech SKU - Retail
It's more money than the normal Ultimate upgrade. I'm still waiting for NewEgg to tell me what it is, but I may not hear back from them. I imagine a lot of people are asking questions about this item. As far as the "upgrade is concerned. It CAN be installed without a previous operating system. The 30 day activation can also be extended to 90 days through the registry--just for your info. The Windows secrets website has the info.

I've really hit a brick wall. NewEgg says they don't know what it is---but they sell it---for MORE money than the standard Vista upgrade. They tell me I have to ask Microsoft what it is. Thank you, NewEgg. Here is the link: http://www.newegg.com/Product/Prod [...] 832116155. The TECH SKU costs $327.99 and the NON-TECH SKU costs $249.99. There are also "TECH SKU's" for Office software. I don't know about anyone else, but I am staying away from "BUYING" Vista until the smoke clears and some questions are answered. Perhaps someone in these forums knows someone --- who knows someone --- who might know someone at Microsoft and can find out what the "TECH SKU" is!