.. notation for structs is not covered in Rust book or reference

[frewsxcv]

For example:

struct MyStruct {
    pub a: i64,
    pub b: i64,
}

fn main() {
    let existing = MyStruct {a: 50, b: 50};
    MyStruct {
        a: 100,
        ..existing
    };
}

The .. notation does not appear in the book or the reference

[frewsxcv]

Nevermind. Found it in http://doc.rust-lang.org/reference.html#structure-expressions