Vim's "ga" and utf-8 characters: What is <M-x>?

Question

I pasted text A ∩ B into Vim in order to figure out how the "cap" character is represented.

Using its code, I would then figure out the right commands to print it out from a data analysis environment (specifically, Matlab, though that's not relevant to the question at this point).

The Bash command file ~/tmp/tmp.txt (where the text was pasted) shows that the encoding is UTF-8. So I did some web searching about UTF-8, Unicode, and ASCII.

In Vim, :help :ga says that it prints out the ASCII code. For the "cap" character, it prints <∩> 8745, Hex 2229, Oct 21051, Digr (U. The Hex code is two bytes. From web searching, I'm finding that UTF-8 uses a variable number of bytes, with the first 127 ASCII characters taking up one byte. Since the most significant of 8 bits is for 128+, I assume that 128+ ASCII values take more than one byte because the most significant bit is used as a flag that one more byte is needed for the UTF-8 encoding.

The help for :ga says nothing about Unicode or UTF-8. It says that when a character is larger than 127, the <M-x> form is also printed. Pressing Ctrl+] on <M-x> doesn't warp me to an explanation of what it is. I can't seem to find anything on the internet.

Can someone please point me to an explanation?

P.S. I am not exploring :g8, but I am curious about <M-x>.

Answer 1

<M-x> is the notation for Altx on a PC or Optionx on a Mac.

I understand that you would like to enter the ∩ ("cap") character easily, ideally using Altx. I doubt that it is possible.

But maybe a good alternative is the digraph.

The ga commands tells you that you can input it in insert mode it using the sequence:

Ctrlk ( U

Another solution is to use the Unicode code:

Ctrlv u2229

If you want to know the utf8 code of the character you can use the g8 command (that will return for the "cap" character e2 88 a9).

Remark: There is a simple logic that deduce the utf8 code from the Unicode value.