> For the complete documentation index, see [llms.txt](https://docs.v2.like.co/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.v2.like.co/depub/what-is-iscn.md). # ISCN ISCN ([International Standard Content Number](https://iscn.io/)) is the unique metadata record of a piece of content registered on the LikeCoin chain. The use case of ISCN is similar to that of ISBN (International Standard Book Number) for books being published. The process of publishing content to the [LikeCoin chain](https://www.mintscan.io/likecoin) is more or less the same: a unique ISCN is generated for each piece of content and bears corresponding metadata such as authors, publication date, copyright licenses, and the digital fingerprint. ISCN data is immutable due to blockchain's characteristics. The ISCN data structure supports content versioning, and each ISCN record will connect to its previous version. Registering an ISCN costs [LikeCoin](https://like.co/), which includes the GAS fee and the cost for the application service provider. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.v2.like.co/depub/what-is-iscn.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.