The 72 melakarta raagas are split into 12 groups called chakras, each containing 6 raagas. The raagas within the chakra differ only in the dhaivatham and nishadham. The name of each of the 12 chakras suggest their ordinal number as well.
Indu stands for the moon, of which we have only one - hence it is the first chakra.
Netra means eyes, of which we have two - hence it is the second.
Agni is the third chakra as it denotes the three divyagnis (fire, lightning and Sun).
Veda denoting four Vedas is the name of the fourth chakra.
Bana comes fifth as it stands for the five banas of Manmadan.
Rutu is the sixth chakra standing for the 6 seasons of Hindu calendar.
Rishi meaning sage, is the seventh chakra representing the seven sages.
Vasu stands for the eight vasus of Hinduism.
Brahma comes next of which there are 9.
Disi denotes the tenth chakra after the ten directions.
Rudra denotes the 11 Rudras.
Aditya is the Twelfth which denotes the twelve suns
Rules for Melakarta
There are several characteristic a raaga must follow in order to qualify as Melakarta raaga.
- Sampoorna raaga - which means they contain all seven notes (swara's) of the octave in both ascending and descending scale
- Krama sampoorna raaga - the sequence is strictly ascending and descending in the scales, without any jumps or zigzag notes is followed
- The upper shadjam is included in the raaga scale (ragas like Punnagavarali is not melakarta as they end with nishadham). The ascending and descending scales must have the same notes
Determining the Melakartha
A hundred years after Venkatamakhin's time the Katapayadi sankhya (The Katapayadi sankhya is a way of determining the number of a melakarta raaga from the first two syllables of the name of the raaga) rule came to be applied to the nomenclature of the melakarta raagas. below is the table of Katapayadi sankhya.
This version of sankhya is based on the Roman alphabets. The digits corresponding to the first two syllables of the name of a raaga, when reversed, give the index of the raga. For example, Ramapriya raaga starts with syllables Ra and ma, which have numbers 2 and 5 associated with them. If you reverse them, you'll get 52. Hence, Ramapriya is the 52nd melakarta raga