Notation I can't understand in Quake source code (C)

Question

I was taking a look at the Quake 1 GPL Code and I came across various similar header files, the purpose or use of which I don't seem to understand. They look like tables of some sorts and are structured like this

{1, 0},
{1, -1},
{1, -2},
{1, -3},
{1, -4},
{1, -5},[...]

Without anything before or after them. I understand they define something but I've never come across this kind of notation in C. You can read one of the header files I'm referring to here.

My question is: what are those...things? The ASM is actually giving me less problems than that stuff.

Answer 1

These are probably multi-use includes. They can be used like so:

struct {int y; int y;} points[] = {
#include <points.inl>
};

Answer 2

The contents of a header do not have to be valid C; the C preprocessor will insert them wherever the #include directive is found, such as in the middle of a struct initialization in another source file. As long as it's valid C by the time it actually gets to the compiler, that's all that matters.

Answer 3

They can be used to initialize arrays.

You could use them like this:

int array[N][2] =
#include <header_file>
;