[SunHELP] .rhosts question

[sunhelp at sunhelp.org]

All,
Does anyone know what is the difference between "+" and "+ +" on .rhosts
file?
Here is the issue that I have, I have two machines (A and B), same
configuration, running NIS+ .
machine A, user A has .rhosts with +, user B rlogin to machine A, it works.
machine B, user A has .rhosts with +, user B rlogin to machine A, it
doesn't work. But if user A put "+ +", then B can do rlogin.

Can someone let me know why??
Thanks

William