SERVERNAME
From UODemo Wiki
SERVERNAME is a environment variable you can set to have the UO Gold Demo operate on a subdirectory other than the default "uogolddemo". However, doing this on the default uodemo.exe will actually make the demo stop because it cannot find that directory inside UODEMO.DAT.
To make this work, UODEMO.DAT needs to be edited to include the new server directory.