Thanks Tim,
That is a great subnet-calculator. I had looked at others. Like others coming up to speed on pfsense I was looking at the drape 2.1 book, but at the specifics for setting the IP address. It was pretty terse. Well, I was just looking in the wrong place I suppose.
Your comment prompted me to search for mask in the same document and I found the section, Understanding CIDR Subnet Mask Notation, which of course makes it clear that CIDR is the default means of specifying a subnet …
Thanks again. I wish I was still at the customer site to test it!
pew