Del. Code tit. 29, § 5919

The rules shall provide for the establishment of referral lists for appointment and promotion. Such lists shall include the names of successful candidates in the order of their relative performance in the particular examinations, except where such lists contain fewer than 31 candidates, in which case the names of the successful candidates may be listed in alphabetical order. In the event that the score of the thirtieth name is tied with other candidates, all tied scores will be placed on the referral list even if it exceeds 30. Vacant positions in pay grades 1-5 will be filled by agency recruitment efforts unless a referral list is required by federal law for that position.