All hound tri is - is a black blanket pattern sable. She has that-therefore hound tri. The extent of that blanket pattern changes just like in german shepherds and with luck of spotting we can clearly identify the color. Sometimes- life isn't that nice and if she only had facial markings I would have called her a sable most likely. Her sisters are sables because they have clearly brown pattern spots where there would be that blanket pattern. Braylor's papillons has a great colors section that covers what is hound tri - and where the mystery line is between sable and hound tri, often times it depends on the eye of the beholder.. Like most of the papillon colors besides black and white there is a ton of variations in tris both hound and classic and sables.
I think I would still call her a sable, but I know there's a lot of debate about hounds vs sable. My Mia is a hound tri but she's about the darkest hound I've ever seen. Mia's body patch is solid black like a true tricolor.
Okay so hound tri is essentially a creeping tan pattern like seen in beagles, etc (hence the hound), right? Mia started out looking like a traditional tricolor but her tan spread over her whole face.
I often use Brandi's site for colors. I also use Aleda-Letit's color site a lot too.