It's not about COBOL; it's about the operating system and hardware on which they were written. Manipulation would have been via JCL (if from a mainframe) rathe

It's not about COBOL; it's about the operating system and hardware on which they were written. Manipulation would have been via JCL (if from a mainframe) rather than from within a program. It was typical to have a multi-file header with volume information (e.g. a unique tape ID, encoding details such as BPI and number of tracks), file details (name, creating program, record size and block size if fixed, etc.) In the mainframe example, JCL tweaks could let you bypass any automatic label processing and get directly to the files if they are intact. [EDIT]: I didn't see the part about "severe mould" initially; I think that would make recovery a non-starter.