How can a mandatory field be configured?

The settings for the fields that should not be empty, which means the mandatory fields, must be configured on two different places.

First you have to open the DocuWare Administration and switch to "File Cabinets" --> "YOUR CABINET" --> "Fields" --> "YOUR FIELDNAME" and set the option "Not empty".
After that, you have to give the rights to the users, using a file cabinet profile. For this action you have to deactivate the option "Field can be emtpy".

Please consider that this restriction does not work when the right "ArchiveUser" is assigned in the file cabinet profile.