Replying to the title here, but from my experience knowing how to program COBOL was only one small part of the problem at my previous employer. Knowing what the

Replying to the title here, but from my experience knowing how to program COBOL was only one small part of the problem at my previous employer. Knowing what the programs where doing and what other programs the output affected mattered much more. Such knowledge was not set in documentation but rather in people's heads, more often than not that knowledge disappeared as soon as the person that had been working in that part of the system retired.