A note on “prescriptive” and “descriptive” notation -
Descriptive notation is svarasthana based notation that provides more details about the specific way “notes” are to be handled. Originally, the term “descriptive notation” was coined by ethnomusicologist Charles Seeger to talk about notation of a performance that was created for the purpose of describing the performance in as much detail as the musicologist needs to cover, usually exceeding conventional published levels of detail. He used the term “prescriptive notation” to talk about notation that was intended to be prescriptions for performers as to what to perform when rendering a piece.
In the recent context of Carnatic music, the two terms have taken on different meanings, although not very far off from the original notion. “Prescriptive notation” has come to mean the sparse notation that forms the bulk of Carnatic music notations published. Some musicologists who wish to dive deeper make use of graphical symbols to indicate gamakas to be used in the rendition of a piece. This is also “prescriptive” in the sense of it being instructions to performers.
The original notion of “descriptive notation” is not part of common practice in Carnatic music - i.e. rasikas and music publishers seldom engage in the activity of transcribing what was actually performed into notation for consumption by others. However, this function does exist in the classroom, where a teacher may describe a movement in more detail for the student to understand it both by feeling and by intellect. While in the classroom this is usually recited and not written down, the notion of “descriptive notation” used on patantara is in the sense of these uttered descriptions being written down.