On behalf of a minor, a parent or guardian of the person of the minor may apply, under this section, for admission of the minor to: Any facility that is not a State facility; or The following State facilities: A regional institute for children and adolescents; and The child or adolescent unit of a State facility. The applicant shall submit a formal, written application that contains the personal information and is on the form required by the Administration. A facility may not admit an individual under this section unless: The individual has a mental disorder; The mental disorder is susceptible to care or treatment; The applicant understands the nature of a request for admission; and Assent to the admission has been given: By the admitting physician of the facility; or For a child or adolescent unit of a State facility, by: 1 physician and 1 psychologist; 2 physicians; 1 physician and 1 psychiatric nurse practitioner; 1 physician and 1 licensed certified social worker–clinical; or 1 physician and 1 licensed clinical professional counselor. An admission under this section to a child or adolescent unit of a State facility may not exceed 20 days.