How does one provide proper attribution to files with missing file header?

[Jarielle Catbagan]

Some of the existing core files in the BBB port in the Umon sources
have missing file headers that would normally provide proper
attribution.  How does one provide proper attribution in order to
strive for consistency?  Would it be considered OK to just put the
default attribution to the original author, Ed Sutter, and have a list
following indicating those who made modifications?  What is the best
way to approach this?

Please excuse me if some of the questions appear to be trivial.