Danish to English Other Human Resources personnel's holiday

In a spreadsheet of options for software to give an overview of departments and staffing levels, holidays, etc.
Det skal vaere muligt at varsle (vha. alarmer) adf. leder om medarbejderes manglende afholdt ferie.
My brain's gone silly at the moment - is this an employee having no holiday left to take, or not having taken holidays and instead accumulating them to carry over/potentially lose some?
Sorry if this seems a really basic question!