If you assign a document or questionnaire the Restricted - High or Restricted - Severe security level, you have the ability to allow other users who are not assigned to this document/questionnaire to access it as if they were assigned to it. As assigned users, where other allowed users can access the document/questionnaire depends on their roles, system permissions, and the security level.
Select other allowed users in the same way as you select users in the Assignees step (see Designating Assignees).