This is information on the nature and physical format of a document.
Content Designators
Medium Designators
Place designators in square brackets between the title and the period.
From CSE Manual 9th ed., Ch. 29.3.3.4 Content and Medium Designators
Content designators:
Armann JP et al. SARS-CoV-2 IgG antibodies in adolescent students and their teachers in Saxony, Germany (SchoolCoviDD19): persistent low seroprevalence and transmission rates between May and October 2020 [preprint]. medRxiv 2020; 2020.07.16.20155143. https://doi.org/10.1101/2020.07.16.20155143
Medium designator:
Goldie S. A calendar of letters of Florence Nightingale [microfiche]. Oxford Microfilm Publications; 1977.