The Built for Life workshop asked how we might construct software that outlive its creators. The workshop was organized by AndrewHunt, BrianMarick, AndySchneider, and DaveThomas and held at OOPSLA 2002 in Seattle, Washington, USA.
I encouraged the group to take positive action, even if modest. The result was the Built for Life Number, the simplest hyperlink that could possibly work, and a new responsibility to employ them while PairProgramming.
I developed the mockup of the BFL number allocator as a wiki while on the Bainbridge Ferry out of Seattle. site 
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You've found some code that has a BuiltForLifeNumber something like BFL12887. You can find code and documents related to this code by searching your own directories. In unix you would use a command like:
grep -r BFL12887 src
You can also check the bfl site for an answer related to the code you find. The answer is to the question, Why?