We are having an interesting discussion on the border terrier list about what constitutes a breeder's "line."  I'd like to know what folks here have to say.  There is a lot in the canine literature about what a "line" is.  This is what I wrote:  A bloodline is established based on extensive knowledge of other known bloodlines, hence Primrose (my border terrier kennel name) where I used a brood bitch from a particular breeder that possessed traits I wanted to continue with, but also that I knew I could enhance.  We have a "standard" which is the benchmark for each breeding that is done, only the pups that meet the "standard" are retained in the breeding pool.  And there is line breeding, inbreeding, and out-crossed breeding among the quality lines within the formulation of the bloodline. What constitutes a bloodline is the dogs breed true for the trait or traits that the breeder is aiming for.