The Signature Series was a program where an artist would design a model, and then the Stone Co employees painted them. Each model had a stylized sticker of the artists' signature, and came with a Certificate of Ownership.
4WJF is a glossy chestnut appaloosa on the ISH. Most were mares, but about 15 were made as stallions. This model was designed by Elena Christopher (aka Elaine Stone). Shown below with the weanling Jessie (not made as a set).