Footnote in a footnote.

Invented by Brian Scearce (according to PeterVanDerLinden, see 
http://rtfm.rdslink.ro/Books/C/Prentice_Hall-Expert_C_Programming_Deep_Secrets.pdf page 19).

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Invented by whom?  Well, on a completely unrelated note, I had a chemistry teacher who wrote his
own chemistry book (or rather, lecture notes).  He was very fond of footnotes, and used asteriks
for footnotes.  Just a single one (*) for the first one, two (**) for the second one, and so on. 
The maximum I ever counted was nine (*********), which is quite hard to distinguish from the
eight before (********).  Anyhow, if in the footnote there was another footnote, he used numbers: (1),
(2), (3), and so on in regular footnotes.  On the second level (footnotes of footnotes), he used two-digit 
numbers (11), (12), to nest another level.  I remember a footnote like (1324).  Needless to say, I 
(literally) burneded the notes after the course...