Why are there two shortcut keys for inserting symbols?

[Meghan]

I was wondering why there are two shortcut keys for inserting symbols in
Microsoft Word? One with Alt+numbers, and one with Alt+Ctrl+symbol. It is
quite confusing to see one shortcut key in the list of symbols, and the other
shortcut key in list of recently used symbols.

 

[Jezebel]

Actually there's a third: [nnn]alt-x where [nnnn] is the hexadecimal
character number.

Alt-Ctrl-character works only for a very few, mnemonically-coded symbols
like Copyright and Trademark. Alt-nnn was intended for the entire character
set but works only for three-digit character codes (ie pre-Unicode).
[nnnn]alt-x is intended to work for the much larger Unicode character set.