To know if Microsoft .NET Framework 3.5 is enabled or installed, we can use Custom Inventory Rule.
Refer to this Microsoft KB, we can use this Custom Inventory Rule syntax below to detect it:
RegistryValueEquals(HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\v3.5, Install, 1
Please refer to page 405 of the K1000 Admin Guide to create a Custom Inventory Rule.
If the Microsoft .NET Framework 3.5 is enabled or installed in the target machine, this Custom Inventory Rule item will be list under Installed Programs in Inventory Detail.
