[NTG-context] tables with notes

I have a dim recollection that this question has been asked before, but I have not been able to find the answer. So please excuse me if this goes over old ground. I have prepared a fairly complex table (using \starttables) that has notes to various entries. What I should like is to • mark the notes with the letters, a, b, c,... • put the notes immediately beneath the table caption (in single column text) and to keep the notes with the table, and • maintain the proper sequence of numbered footnotes in the surrounding text. Any suggestions or pointers to previous discussions will be gratefully received. Alan