# URNs A [URN (Uniform Resource Name)](https://datatracker.ietf.org/doc/html/rfc8141) is a standard format for identifying online resources. They are used throughout Trovi to represent various forms of data. A URN is a string in the format of \ `urn::`. `nid` stands for "namespace identifier," and `nss` stands for "namespace-specific string." The NID is a single word which represents the entity which created the URN. NIDs are officially registered with IANA, but in theory, they can be anything. Trovi has an unofficial NID of `trovi`. Anything not belonging to an official namespace will use the `trovi` NID. So, for example, a Chameleon Cloud user URN will be formatted `urn:trovi:user:chameleon:`, because Chameleon Cloud does not have an official NID. The only official NIDs we use are `ietf`, which are used in [tokengrant](https://chameleoncloud.gitbook.io/trovi/api-reference/token/tokengrant "mention") requests, and `globus`, which may appear in linked resources in [artifact-versions](https://chameleoncloud.gitbook.io/trovi/api-reference/artifacts/artifact-versions "mention"). --- # Agent Instructions: 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: ``` GET https://chameleoncloud.gitbook.io/trovi/urns.md?ask= ``` The question should be specific, self-contained, and written in natural language. 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.