Does any one know how this Percentage-normalized Signal has been calculated?

Question

[Lila M]

Hi everybody, I'm, trying to follow this protocol using my own files, but I'm a bit stuck because I don't know how they get the bigwig files. Apparently the "replication signals at each location were determined as a percentage of the sum of the six normalized tag density signals", but does anyone knows which programs did they use for doing this? Many thanks!