%%Writers often used Hát Nói - a very popular form in ca trù - when declaiming poems. Hát Nói referred to "singing while speaking". It was required for the song to have the specific rhythm and outline. The proper song included 11 sentences inserted with 2-4 verses having 5-7 words each in style of Đường poetry. The last sentence was called the summary sentence with 6 words in six-eight style.