# Yulia Khalniyazova - Taiga Book - Notes (Highlights)  ## Metadata **Review**:: [readwise.io](https://readwise.io/bookreview/33228948) **Source**:: #from/readwise #from/reader **Zettel**:: #zettel/fleeting **Status**:: #x **Authors**:: [[Yulia Khalniyazova]] **Full Title**:: Taiga Book - Notes **Category**:: #articles #readwise/articles **Category Icon**:: 📰 **URL**:: [github.com](https://github.com/anoma/taiga/blob/main/book/src/notes.md) **Host**:: [[github.com]] **Highlighted**:: [[2023-10-16]] **Created**:: [[2023-10-16]] ## Highlights - A **note** is an immutable object that represents a part of the application state. Each note belongs to a certain application (that defines the note's type), and can store some data. As notes are immutable, notes cannot be modified, only spent or created. "Modifying" a note would be done by spending the current note and creating a new note of the same type and modified fields. ([View Highlight](https://read.readwise.io/read/01hcv2b6w1qevrxtxrfzr6a2a3)) ^611212149 Similar to CKB cell - Each created note is added to a public Merkle tree. ([View Highlight](https://read.readwise.io/read/01hcv2d81mq54s88xgc4q4556e)) ^611212273 CKB cells commitment - Notes are never deleted from the note commitment tree, and to signal that the note has been spent and isn't valid anymore, its nullifier `nf` is added to the public nullifier set. ([View Highlight](https://read.readwise.io/read/01hcv2dzej27j4zc2fvw0jxg64)) ^611213153 However, it requires proof that `nf` is not published. - However, no matter what meaning the application gives to the value, Taiga isn't aware of that and uses the `value` field of notes to check the transaction balance. ([View Highlight](https://read.readwise.io/read/01hcv2hehfktp3e82k5a9aq2dd)) ^611213561 A universal value field for balance. - Each note contains a commitment to the nullifier key `nk` of the note's owner. Whoever knows the nullifier key, can compute the note's nullifier and spend the note. ([View Highlight](https://read.readwise.io/read/01hcv2kq6zascqvq9d1jrba6pa)) ^611213731 <!-- New highlights added October 19, 2023 at 8:09 PM --> - Some notes in Taiga can be dummy, meaning that unlike "normal" notes, the merkle path isn't checked for them, but they can have arbitrary value and are stored in the commitment tree, just like "normal". ([View Highlight](https://read.readwise.io/read/01hcvnnnkjncn65rw35v2jxf0e)) ^611331350