0: Test for source tree numbering 0: Level A 0: Level B 0: Level B 0: Level C 0: Level B 0: Level C 0: Level D 0: Level A 0: Level B 0: Level C 0: Level D 0: Level E 0: Level A 0: Level B 0: Level C 0: Level D 0: Level E 0: Level D 0: Level E 0: Level C 0: Level D 0: Level B