DataStore_Agenda is part of the DataStore series.
Its purpose is to scan and store data related to Calendar, Raid ids, Friend List (and later to-do-lists, personal notes, and maybe more) for all your characters, and act as a data abstraction layer for client addons, which no longer have to scan or store this information.
More information can be found on the main page : DataStore
Specific details (usage/scope) will be posted later as separate pages on this project.