Enum within struct - Scope of enum in C

Why I can use the enum "outside" the struct as a parameter of the init function? So it looks like the enum is global and not restricted to the enclosing struct block.

typedef struct {
    double x;
    double y;
    enum color_t {r, g, b} color;
} point;

void myfunc(point *this, enum color_t c) {
    // TODO
}