For keeping an external database of a third-party (learning environment)-software consistent to Moodle's database via an acitivity-module - this module hast to be informed about certain events out of the core. The events and the information we would like to see are:

1.1 update of a user's profile (either by an admin of the user himself)
information we need: user's name and surname, loginname, encrypted password, id of user-table and the idnumber
but we suggest to keep all information that have changed or the whole form (perhaps other later modules could use this information, too)
1.2 deleting a user's profile
information: user-id of the user-table
2.1 update of a course
information needed: id, category-id, fullname, summary
but again we suggest to keep everything changed or the whole form
2.2 deleting a course
information needed: the deleted course (at least it's id)
3.1 update of a category
information needed: id, name
3.2 deleting a category
information needed: id of the deleted category and the upper category the courses are switched to (at leased it's id)
4.1 creating an new group in a course
information needed: id, name, description, course-id, grouping-id (and -name or NULL if no grouping)
again our suggestion to keep the whole form (if later modules need to have more information than our's)
4.2 updae of a group
information needed is the same as above (better: the whole form)
4.3 add a user to a group
information needed: user (at least it's id) and group (at least it's id)
4.4 remove a user from a a group
information needed is the same as abov
4.5 deleting a group
information needed: group-id