How does Dnadiff deal with gap penalties?

Question

[caro-ca]

Hi, community! For evaluating correctness, I aligned two similar draft assemblies using nucmer from MUMmer. To get the statistics of the alignment I used dnadiff. However, I do not know how the gap penalties work. I've been looking for literature, but there is nothing about dnadiff.

I hope you could recommend me some papers or help me out. Thanks in advance.