I am a bit confused about the compatible bit. Surely this does not mean they are closely related? Why would you want to in-breed dogs too much? I know to keep the right look etc, but surely it is better to get some fresh genes in every now and again?
Thanks for any info.

Hi,
Within a breed you often find that there are lines that simply don't 'work' when put together...excellent though they may be individually, and when put with dogs from different lines they get good results, when put with others the resulting litter can be mediocre at best. It takes a lot of detailed research and enquiry to find out if it's promising or a waste of time.

As a general rule, mating individuals with mutual great or great-great grandparents is likely to work quite well. With a complete outcross the outcome is in the lap of the gods!
:)