: Test for source tree numbering .A: Level A .A+a: Level B .A+b: Level B .A+b 1: Level C .A+c: Level B .A+c 1: Level C .A+c 1 1: Level D .B: Level A .B+a: Level B .B+a 1: Level C .B+a 1 1: Level D .B+a 1 1 1: Level E .C: Level A .C+a: Level B .C+a 1: Level C .C+a 1 1: Level D .C+a 1 1 1: Level E .C+a 1 2: Level D .C+a 1 2 1: Level E .C+a 2: Level C .C+a 2 1: Level D .C+b: Level B