> For the complete documentation index, see [llms.txt](https://docs.chainlife.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.chainlife.xyz/chainlife-tech/token-tech.md).

# Token Tech

Chainlife NFTs are ERC-721 compliant tokens on Ethereum. Matto wrote the smart contract that deviates from a standard token contract in a few ways:

* Transfers are counted for every token
* The prior owner of every token is tracked.
* There are two pieces of user-settable pieces of on-chain data:
  * Level Shift allows owners to adjust the world-level their token lives on.
  * Custom Rule allows owners to set the ruleset that control their token's population.
* A custom minting function checks ownership of Matto's Art Blocks projects, acting as a gate that only allows collectors to mint during that phase.
* Generative scripts can be stored on-chain, for use to recreate token art
* A single call to the contract returns all the various information that the generative script requires (token ID, random hash, owner, prior owner, transfer count, shift level, custom rule)