list of special characters

I don't know if this is a complete list, but here's what I know:
%%c = Ø (circle dimension, or diameter. Also Greek letter Phi) %%d = ° (degree) %%o = overscore, or "overline" (opposite of underline) %%p = tolerance (plus/minus) symbol %%u = underlines what comes next. %%% = percent symbol
Also, you can draw many Unicode symbols this way:
\U+HHHH, where HHHH is the Unicode symbol number in hexadecimal
For example:
\U+00B0 = degree

I knew those ones,
will delve into this site more, may have what I'm looking for, one in particular is superscript 2 for 'squared'. thx for the link