I have been just such a consultant&#x2F;employee doing this, even started calling it software archaeology some time in the &#x27;90s.  It&#x27;s a very painful way of earning money, but there&#x27;s a whole lot of &quot;poorly documented or undocumented legacy software implementations&quot; out there.  Generally effectively undocumented, for many projects start out with some documentation, don&#x27;t keep it up to date, and by the time you get your hands on the mess it all, including comments, are more a statement of intention at one point in time than something directly and immediately useful.