We would like to use the idea of Minimal reference phylogeny for the human Y chromosome
and to use only those mutations which divide subclades of Baltic Sea DNA Project participants.
List of haplogroups is wider than capital letters, we use R1a, R1b, I1, I2 J1, J2 for example
See: https://www.familytreedna.com/public/y-dna-haplotree/ and https://www.yfull.com/tree/
Subclades you can see on Result page: https://www.familytreedna.com/public/balticsea?iframe=yresults