This feature will be usefull if for one set of joints you need to use two (or more) distinct SN curves along the jacket life time (typically a S-N curve with paint in the first 15 years and free corrosion at the end of the jacket life)

This way we will be able to combine the damages from a first analysis using S-N curve "A" and a second using S-N curve "B".

It would result in a combined ftgext.* file in which the combined damage would be visualized and the joints could be redesigned.