Yesterday, I updated my system to current version by the "Tracking
NetBSD-current".

When I run the command "etcupdate -b /sandbox/current", it gave me a
warning. And then I read the manual and knew that I should use "-s"
option instead of the "-b" in NetBSD4.0.

So, I think the step 4 in the "Installing a current snapshot" section
of the "Tracking NetBSD-current" should be updated or append with some
comments at least.

Thanks for your work.