Source is an original in the Netherlands “Jan dirk nijkamp” it’s is 100% definitely recessive white. The form of recessive white in Bobtail is not what we commonly refer to as recessive white, in other words  not bright white. It may, however, be an allele. We don't know for sure as no one has done the test mating to find out. It is an autosomal recessive, so not sex-linked. By brown I do mean the Brown e-allele (eb). The gene must be present in two copies (homozygous) in order to present as Bobtail.