In information technology, a trailer or footer refers to supplemental data placed at the end of a block of data being stored or transmitted, which may contain information for the handling of the data block, or simply mark the block's end. Wikipedia

Data appended to a main block of data to facilitate its processing Wikipedia Disambiguation

supplemental data placed after a block of data being transmitted Wikidata

The final record of a list of data items, often identified by a key field with an otherwise invalid value that sorts last alphabetically (e.g., “ZZZZZ”) or numerically (“99999”); especially common in the context of punched cards, where the final card is called a trailer card. Wiktionary