• String

Sets the series name that BGM appreciation should collect this music into. If this parameter is omitted or the series name is empty, the music is collected into the default series.

Default Series
  | - BGM Name 1
  | - BGM Name 2
Series Name 1
  | - BGM Name 3
  | - BGM Name 4
  | - BGM Name 5
Series Name 2
  | - BGM Name 6

The same music file, strictly speaking the same path, can only belong to one series. If it is collected into multiple series, only the series from the last collection is kept.