When creating an assignment add the functionality to choose a list a file format allowed for the file the student will upload.

A multi-selection component is used with predefined extensions, and you can add a custom extension via an input text.

Default extension are : pdf, docx, xlsx, zip, mp3, mp4
(@todo on another issue: add in the Chamilo Admin Tool configuration page the possibility to customize the default list)

When upload his assignment, a line show the student allowed file format.
He gots an error message if his file's extension have a wrong format.