What is the correct terminology for this array literal of struct literals?

I recently ran into this method of declaring an array of structs, but could find any documentation on it anywhere since I don't know what to search for. What is this called? -and/or- Where is this syntax documented?

struct point {
    int x;
    int y;
};

// This right here:
static struct point points[3] = {
    [0] = { .x = 1, .y = 2 },
    [2] = { .x = 4, .y = 2 },
    [1] = { .x = 0, .y = 3 },
};

(My apologies if this is the wrong place to post this kind of question.)