DF63 is the oldest haplogroup below L21 and the only major branch next to DF13. With this DNA test we start with 3 key SNPs
A91
Z16506
BY592
and then we work down the branches iteratively until we have found your position on the given tree.
The test is completed when the unique phylogenetic position on the tree has been determined.
See this tree diagram to understand the groupings in this panel:
