Why are there two nested curly braces without any statement in-between?

The code given below is the code generated by MOC in Qt.

const QMetaObject MainWindow::staticMetaObject = { 开发者_StackOverflow中文版 { &QMainWindow::staticMetaObject, qt_meta_stringdata_MainWindow, qt_meta_data_MainWindow, 0 } };

Why is there two continuous curly braces without anything statement in-between? Also, what does the statement mean? Just comma separated variable means anything?

I think it is initializing a list (external braces) of structure (internal braces.)