Request for documentation of -XX:+PrintTenuringDistribution output

The customer has requested some kind of documentation to clarify -XX:+PrintTenuringDistribution output: "How to read the gc log files ? What does age1, age2 mean and two columns after that?"

e.g: Desired survivor size 48286924 bytes, new threshold 10 (max 10)
- age 1: 28992024 bytes, 28992024 total
- age 2: 1366864 bytes, 30358888 total
- age 3: 1425912 bytes, 31784800 total