Titel aanvullen; Título suplementario; Täydennä otsikko; Ergänzungstitel.
This is different to sections within the layout.
Supplement to the Sydney Gazette and New South Wales Advertiser, 7 August 1813: 1. Trove.
“Supplements sustained their parent titles, contributed to their formal organization and enhanced their editorial contents.” [DNCJ, LRB, 610]
“The Weekly Dispatch not only emphasized its connection to Cook by distributing her portrait as a newspaper supplement but also capitalized on her fame by frequently mentioning her name in advertisements aimed at potential subscribers.” [Easley 2016a, 698]
“He was an associate editor of the Sunday supplement.” [Kwiat, 102]