They contain snippets of solfege to be used when performing the mentioned ragas.
From the en.wikipedia.org
The fourth, fifth, sixth and seventh levels are sight singing extensively through the use of solfege.
From the tennessean.com
Born in Hamburg, Berks County, first trained in piano, he was something of a solfege prodigy by age 7, his wife said.
From the orlandosentinel.com
When words do occur in Einstein, they are likely to be numbers or solfege syllables like do, re, mi that are bleached of definition.
From the time.com
An example of didactism in music is the chant Ut queant laxis, which was used by Guido of Arezzo to teach solfege syllables.
From the en.wikipedia.org
As with movable do solfege, the notes are heard relative to an arbitrary tonic that varies from performance to performance, rather than to fixed frequencies, as on a xylophone.
From the en.wikipedia.org
More examples
Solmization: singing using solfa syllables to denote the notes of the scale of C major
A voice exercise; singing scales or runs to the same syllable
In music, solfu00E8ge (US /su0252lu02C8fu025Bu0292/, UK /u02C8su0252lfu025Bu0292/, French:u00A0) or solfeggio (/su0252lu02C8fu025Bdu0292u026Aou028A/, Italian:u00A0), also called sol-fa, solfa, solfeo, solfeggio, among many names, is a music education method used to teach pitch and sight singing Western music...
A method of sight singing music that uses the syllables do (originally ut), re, mi, fa, sol (or so), la, and si (or ti) to represent the pitches of the scale, most commonly the major scale. ...
The method of associating each note of a scale with a particular syllable. The modern series is usually doh-ray-me-fah-soh-lah-te, with doh as C in the fixed-doh system and as the key-note in a moveable-doh system. ...