This works:
start %appdata%\Mozilla\Firefox\Profiles\
These do not:
start %localappdata%\Google\Chrome\User Data\
start "%localappdata%\Google\Chrome\User Data\"
start %localappdata%\"Google\Chrome\User Data\"
start %localappdata%"\Google\Chrome\User Data\"
How can I open a Windows Explorer window using a path that has an environment variable and a space?