[Publib] 50 things..

[Andy Barnett]

There's a difference between opt in and opt out. Allow them to opt out, 
instead of requiring them to opt in, since it will be more comfortable 
for them and it is better service.

If you say "Can you find this number?", they have to opt in as unable to 
use the library without your help.

If you say, "Can I show you where this is?", they have to opt out of 
your kind invitation.