This is not a simple (Plain)TeX Reference page or a quick guide to TeX or friends: this is my own reference sheet in wich you can find what I don't find in internet or The TeXBook.

TeX (not LaTeX) is here not the very sistem, but the code of the text to compile with (Plain)TeX (not LaTeX): that is, how do the difficult things simple in (Plain)TeX.

I quote from http://www.topology.org/soft/tex.html (20-IX-07):

"TeX is the venerable and still revolutionary typesetting software from Donald Knuth.
My documents written in TeX in 1985 still work exactly the same now as then.
And TeX is still by far the best typesetting system.
No versionitis. No bugs. And it's free and open.
TeX is what started the open source revolution, not Richard Stallman's FSF."

You can freely copy and paste or download the examplain.tex.

1. Definition of \alph to do enumerations with letters always in (Plain)TeX:

\def\alph #1{ %
\ifcase #1 %
\or a\or b\or c\or d\or e\or f\or g\or h\or i %
\or j\or k\or l\or m\or n\or o\or p\or q\or r %
\or s\or t\or u\or v\or w\or x\or y\or z %
\fi %

2. To do automatic numbering of footnotes define this:

\nnnota= 0
by 1\footnote{$ ^{\the\nnnota}$}}

And then write so:

This is the first note\note{first}, and this is the second\note{second}, and this is the third\note{third}.

3. Now do the same but with letters:

\nnota= 0
by 1\footnote{$ ^{\alph{\the\nnota}}$}}

pay attention to the different number of "n" in the definitions (\nnnota and \nnota).

4. Do you think that the two series could coexist?

Yes. Here you have:

\newcount\nnota \nnota= 0
by 1\footnote{$ ^{\alph{\the\nnota}}$}}