But I think learning Cobol is only about 25% -- the hard parts are knowing what the legacy codes does vs. what it's supposed to do vs. what you really want to d

But I think learning Cobol is only about 25% -- the hard parts are knowing what the legacy codes does vs. what it's supposed to do vs. what you really want to do, understand how and when the Cobol code actually runs on the legacy system (JCLs, schedulers, etc.), understanding what arbitrary limitations you must carry over to your new system, etc. -- all of which is probably not documented very well.