I've recently updated my local Nektar++ version to the latest one in the repository. In this new version, it looks like there are some changes in checkpoint filter. In particular, once in a while the code writes out chk files with a "bak0" extension. What would this extension supposed to mean? I did some research but couldn't find.

I also noticed that the chk file for the same time instance is slightly larger compared to its "bak0" counterpart and to the rest of the fields, for instance:

62G    config_22.chk
62G    config_23.chk
62G    config_24.bak0.chk
64G    config_24.chk
62G    config_25.chk
62G    config_26.chk
62G    config_27.chk
62G    config_28.chk
62G    config_29.chk
62G    config_30.chk
62G    config_31.chk
62G    config_32.chk
62G    config_33.chk
62G    config_34.chk
62G    config_35.chk
62G    config_36.chk
62G    config_37.chk
62G    config_38.bak0.chk
64G    config_38.chk