Thought I had a fair knowledge on this subject....but having used [quite frequently] the pidgen exe [The Ultimate PID Checker v1.1.3.590 by janek2012] to verify different serials I have come across something and I am not sure of the origin/meaning....so I ask for help. Specifically in regard to Windows 7 I have seen listed; Description: Windows 7 Professional OEM:COA Edition ID: X15-37341 Key Type: OEM:COA EULA : OEM Crypto ID: 186 and Description: Windows 7 Professional Retail Edition ID: X15-39021 Key Type: Retail EULA : MSDN Crypto ID: 170 and Description: Windows 7 Ultimate Retail Edition ID: X15-38932 Key Type: Retail EULA : Retail Crypto ID: 170 and Description: Windows 7 Professional OEM:SLP Edition ID: X15-37377 Key Type: OEM:SLP EULA : OEM Crypto ID: 178 and now; Description: Windows 7 Professional OEM:NONSLP Edition ID: X15-37362 Key Type: OEM:NONSLP EULA : OEM so what is the precise meaning of OEM:NONSLP? Is that the category afforded the ubiquitous System Builder OEM available through retailers supposedly for Mum & Dad Computer Stores?