DxD Tools/Verify drc-002 rule "values" format

I'm trying to follow the 7.9.4 tutorial, but I don't understand the string of acceptable values in the drc-002 rules settings

It had me change the "Values" string

from

^(~?[a-zA-Z_0-9+-.]+)$

to

^([a-zA-Z_0-9+-.~$]*)$

so that the characters "~" and "$" are acceptable in net names

What is the significance of removing the "?"

What is the significance of changing the "+" to "*"

Did the position of "~" in the string make a difference?

I tried to click "HELP" from the Verify/Tools dialog, but it doesn't explain the syntax

thanks,

Jack (aka "the new guy")

Here's a pic: