Signing off a report validates the report and sets the corresponding IMPAX study status to Approved. The Sign button 
in the Text area is only enabled for the author and/or reviewer (including a proxy reviewer) if the following conditions are met:
The report is not fully validated.
The report is linked to one or more studies.
If the report is already partially validated, the user matches the report reviewer.
If the report is not yet partially validated, the user matches the report author.
If the report is not yet partially validated, the user matches the report reviewer and the report author is a resident radiologist.
If the IMPAX RIS TEXTAREA.EXTENDED_SIGNOFF_AND_EDIT parameter is enabled, a larger group of users can sign off on a report, not just the assigned reviewers or proxy reviewers. For example, user A creates a new report, assigns user B as the report reviewer, and then user C signs off on the report.