Thank you, Itamar, for your reply and your explanation. I wanted to find out how to control access to a field and use this knowledge in a group peer review activity. For those who want to use "Entry access," here are my steps.
Beside the Dataform module, you need to download the "Dataform entry access" block. Next, set up a new Dataform activity and a field "file" for uploading files. Go to views and add a view. I choose a tabular view and named it "Student's view."
Now log in as a test student and upload a file.
Log in as a teacher again, open the Dataform activity and change the permissions for students. Go to Administration block > Dataform activity > Permissions and select student role in the drop down menu at the top.
Then I changed "own entry - add," "own entry - delete" and "own entry - update" from allow to prevent in the student role.
In the Dataform activity, I selected access.
You should see something like this. When you click on the plus sign (#1), you will get a generic entry access, which you should configure by pressing the wheel icon (#2). The edit icon (#3) is for later.
You only need to fill out the general section (see screenshot below). The dates in "From" and "To" will allow the student to upload, change or delete a file. You do not need to add anything in the filter section.
The configuration will only work with the final step. Click on the "Access" tab and then on the pencil icon (#3), the one between the wheel and the delete icon. Now you need to change the permission for the student role.
Change the student role for "Own Entry - Add/Delete/Update" to allow (see below).
Log in as a test student and see if the access control works.
With kind regards,