the best solution might be to find a time traveler

[OT from cottage renovations]

when looking online for IT gigs it's always intriguing when a position's responsibilities include the following (I didn't make this up; it's lifted straight off the text of a posting):

• Perform reverse-engineering of existing software code into system requirements. 

there are, I suppose, any number of circumstances under which and reasons why this might be necessary.  some of them might even be legitimate.  but it does raise interesting notions of causality and precedence.  once a set of requirements has been created in this fashion, does it become the definitive source for the code?  for testing?  for documentation?