For reporting purposes I wanted to export the Windows 10 Build versions. Not only the Major build version (1709/1803 etc) but also the minor (which patch level). This is how I did that :
Create a new Software title (Inventory/Software) and fill the custom Inventory Rule with the following code :
RegistryValueReturn(HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion,CurrentBuildNumber,text)
Make sure that you select all your Windows 10 devices. Be sure to save the software package. Now create another Software with the following custom Inventory code :
RegistryValueReturn(HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion,UBR,text)
After a force inventory you notice the 2 custom Inventory rules when viewing the device info :
Windows 10 Build versions info here.