"Additional credentials" refers to extra qualifications or achievements that someone possesses, which enhance their skills or expertise in a particular field. Full definition
They are also typically trained as traditional psychologists or psychiatrists but have additional credentials as sexual therapists. (wisegeek.com)
Graduate and professional schools are for people who need additional credentials beyond an undergraduate degree to reach their career goals. (eiu.edu)
Additionally, a registered nurse can obtain additional credentials which allows them to work as Nurse Practitioners, First Assistant, Clinical Nurse Specialist, or Nurse - Midwife. (pregnancy-info.net)