In Ip Man Wing Chun hand techniques are often classified into 3 "families" or categories said to be either Tan, Bong, or Fook. As far as I know, Pin Sun Wing Chun does not classify hand techniques this way, and it never made much sense to me when I was studying Ip Man Wing Chun. So I thought this might make a good topic for discussion. Anyone want to elaborate on what this means and how it is used? Do people find it useful? Or not?