> What would be the use case? Every time you need to extend the length of the field in the middle of your data (e.g., increase a variable-length-field in the h

> What would be the use case? Every time you need to extend the length of the field in the middle of your data (e.g., increase a variable-length-field in the header). Many file formats resort to trailer chunks specifically because of that (see ID3v2 of MP3 files, or ZIP). Or think about how SQLite's on-disk file format uses freelist of file pages: it's literally an embryonic file system in itself, built on top of the existing one. Or hey — what about linking object files together? It's kind of like the merge sort, since you need to re-slice text/data/misc and then re-glue them. Traditional linkers would create several temporary files for each combined section and then merge those files together.