How many people here know what of the dog breed 'Mcnab'?

So I have a dog called a 'Mcnab' stockdog. It's also known as a Mcnab cattledog/herding dog/Border collie. What they are, is a non AKC registered breed (doesn't quite measure up to standards. They vary lookswise too much), that is closely related to a border collie. I got mine from a shelter, and they called her a border collie chocolate lab mix. Then I talked to a lady who breeds Mcnabs and she was positive mine was one. Plus, she perfectly fit all the descriptions online as far as appearance and personality goes. They're usually black, but some are brown, can have prick or kinda floppy ears and have short fur. So, I was just wondering how well known are these dogs? Just say if you knew about them before reading this, if you've met them and your thoughts on them. Just curious. Thanks! :)