Struct Product 

pub struct Product {
    pub id: &'static str,
    pub extension: &'static str,
    pub format: &'static str,
}

What an application tells the shell about itself.

The identifiers are not translated: a desktop entry, a window class and a file extension are the same in every language.

Fields

id: &'static str

The binary’s name, which is also the .desktop entry’s basename and the Wayland application id. The compositor matches the three to find the window’s icon, so they have to agree.

extension: &'static str

The file extension the application opens.

format: &'static str

What the file dialog and the empty window call that kind of file.

The English, which is the message id: it is looked up through t where it is shown, because a Product is built before run puts a catalogue in force and a translation looked up here would be the English every time.