This is something almost limitted to AAR and their ilk...
If you type in something to a txt box, it is saved as a exportable file.
So if I message myself in a single player game, it is able to later exported into a .txt file.
This is absolutely a very lmitted feature.
It would help with game notes " X acted funny, not sure if intendened"
It would help with AARs for sure "Dark spire 10 / 10 + Fallen Spire = Fallen spire Brigands pillaging the country side with human and AI forts"