Like kangofusei (tally system) in the Japan-Ming trade, Gafusei was a system where a tally was split into two halves and used for certifying an envoy where the communication tally called gafu (seal tally) or zogefu (ivory tally) was used in place of the kangofu.
牙符制は日明貿易における勘合符制と同様、一つの符を二つに裂いた割符を以って使節の査証を行なう制度であり、勘合符の代わりに牙符あるいは象牙符とも呼ばれる通信符が使用された。