On http://www.perceptualedge.com/discussion.htm I found this..

“A seemingly small point which deserves special mention is that one should get in the habit of making all charts, tables, reports, and problems complete in themselves.  It should be possible to learn from the sheet, six months after its completion, what the problem was all about, who gathered the data and calculated it, who drew the graph, what were the important conditions at hand, what were the sample size and the units, the date, etc.  Only in this way can we make sure that our records will not grow ‘cold’”

I W Burr, Professor (1941 – 1974), Statistics Dept, Purdue University, Indiana