大方廣圓覺修多羅了義經略疏 1.183

1.183

又上三字是別，圓字是總。意明此覺具足三大之德，故名圓也。是則總別之德具彰，法義之門雙指，故名大方廣圓覺。

Furthermore, the first three characters are specific, and the character "perfect" is general. The intent is to clarify that this enlightenment fully possesses the virtues of the three greats, hence it is called "perfect." Thus the virtues, general and specific, are completely displayed, and the gates of Dharma and meaning are both indicated; therefore it is named "Great Expansive Perfect Enlightenment."