The Seipel pattern refers to the vertical lines of black in the breast feathers of a female black shoulder pattern. I think this was something that showed up in work that Jack Seipel in AZ. done . This was about 30 or so yrs. ago..I breed some every year because I like them, some are darker and fuller than others,,, why ?? in the genes I guess.. The males are very hard to identify so when you get one that breeds this pattern keep track of him. The one I use is a midnigtht BS . I work for a darker stripe and more of them but it is hard to build on this pattern. .Pedda could be correct but I have never seen a spalding BS with this pattern. A few breeders have them because they like the way they look.. George