What are required WinTel Environment Variables?

Howdy,
Did a Google search found this forum.
Did a forum search and the only close question was this one:
http://www.dbasupport.com/forums/showthread.php?t=45128
Which is my question only for Unix, not windows.

I've recently inherited a 10g instance on a WinTel box. The ORACLE work I've done has always been on Unix boxes.

I'm in the process of upgrading from 10gR1 to 10gR2. Reading the guides - environment variables are mentioned. Looking at the Wintel configuration the only two I find set are ORACLE_SID and ORACLE_HOME.

What are needed/required WinTel evironment variables for a 10gR2 Enterprise Edition instance.

Where are they documented? Yes, I do RTFM - it's just that ORACLES FMs are not always as straight forward as I would like.

Thanks