
Bi colours are very rare & always have been, it is an acceptable colour They should be black with tan/gold feet A bit like rottie/dobe markings
"Black or black saddle with tan, or gold to light grey markings. All black, all grey, with lighter or brown markings referred to as Sables. Nose black. Light markings on chest or very pale colour on inside of legs permissible but undesirable, as are whitish nails, red-tipped tails or wishy-washy faded colours defined as lacking in pigmentation. Blues, livers, albinos, whites (i.e. almost pure white dogs with black noses) and near whites highly undesirable. Undercoat, except in all black dogs, usually grey or fawn. Colour in itself is of secondary importance having no effect on character or fitness for work. Final colour of a young dog only ascertained when outer coat has developed"
Here's a
link to a USA site but there's a bi colour there as to the other "colours"no comment