Are students allowed to post any materials on IS?
Yes, they are. Provided a student wants to offer other users some of his/her study materials (e.g. his/her lecture notes), he/she should use the following path:

The Information System Student [course] File Vault

The files can consequently be accessed by all the students enrolled in the course (before the beginning of teaching period this includes all of those who have registered for the course). When preparing study materials for the upcoming term and copying the old ones into it, teachers can include in them also the files uploaded by the students in the past.

The folders Learning Materials, Assignments, Course-Related Instructions and File Vault are created the first time a user enters the tree of the course.