Other compatibility issues

There are a lot of small issues. Some of them should be listed here:

icoFett Icon c:\cavowork\brandnamic\ba-erp\icons\Fett.ico

You need to surround the filename with double apostrophes like this:

icoFett Icon "c:\cavowork\brandnamic\ba-erp\icons\Fett.ico"
function CleanUpServer( oServer ref DataServer ) as void
oServer:Close()
oServer := null_object
return

compiles in VO without any issue when you call it with any subclass of DataServer or DBServer. This is very dangerous and therefore it will not work anymore in X#.