The oral tradition of the Vedas (Śruti) consists of several pathas, "recitations" or ways of chanting the Vedic mantras. Such traditions of Vedic chant are often considered the oldest unbroken oral tradition in existence, the fixation of the Vedic texts (samhitas) as preserved dating to roughly the time of Homer (early Iron Age). UNESCO proclaimed the tradition of Vedic chant a Masterpiece of the Oral and Intangible Heritage of Humanity on November 7, 2008. Vedic chantings use 4 tones – Udatta उदात्त (middle tone), Anudaatta अनुदात्त (lower tone), Svarita स्वरित (higher tone) and Deergha Svarita दीर्घस्वरित (High tone extended). These are usually marked with intuitive svara marks – an underline for lower tone, a small vertical line above the letter for a higher tone and two vertical lines for Deergha Svarita. The various pathas or recitation styles are designed to allow the complete and perfect memorization of the text and its pronunciation, including the Vedic pitch accent. Eleven such ways of reciting the Vedas were designed – Samhita, Pada, Krama, Jata, Maalaa, Sikha, Rekha, Dhwaja, Danda, Rathaa, Ghana, of which Ghana is usually considered the most difficult. The students are first taught to memorize the Vedas using simpler methods like continuous recitation (samhitapatha), word by word recitation (pada patha) in which compounds (sandhi) are dissolved and krama patha (words are arranged in the pattern of ab bc cd ...); before teaching them the eight complex recitation styles. A pathin is a scholar who has mastered the pathas. Thus, a ghanapaathin has learnt the chanting of the scripture up to the advanced stage of ghana. The Ghanapatha or the "Bell" mode of chanting is so called because the words are repeated back and forth in a bell shape. The sonority natural to Vedic chanting is enhanced in Ghana. In Jatapatha, the words are braided together, so to speak, and recited back and forth. The samhita, pada and krama pathas can be described as the natural recitation styles or prakrutipathas.