How to determine the maximum and minimum of input delay?

Hi slacker!

The timequest user guide (http://alterawiki.com/wiki/timequest_user_guide) is so great,thank you very much!

The output delay and input delay are so puzzling,the output delay waveform shows that the ext_clk move forward 4ns but the out put delay shows 4ns and the ext_clk delay 1ns the out put delay shows -1ns,its't unbelievable.But the input delay waveform is significantly different from output delay.

thank you!