: Test for source tree numbering A: Level A A.a: Level B A.b: Level B A.b+a: Level C A.c: Level B A.c+a: Level C A.c+a+a: Level D B: Level A B.a: Level B B.a+a: Level C B.a+a+a: Level D B.a+a+a+a: Level E C: Level A C.a: Level B C.a+a: Level C C.a+a+a: Level D C.a+a+a+a: Level E C.a+a+b: Level D C.a+a+b+a: Level E C.a+b: Level C C.a+b+a: Level D C.b: Level B