> For the complete documentation index, see [llms.txt](https://docs.zerolabs.green/zerolabs-tokenization-module/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.zerolabs.green/zerolabs-tokenization-module/domain-definitions/issuer/topics.md).

# Topics

Part of the [ERC-1888 standard](https://github.com/ethereum/EIPs/issues/1888).\
\
**Topic** is a number which represents the topic of the certificate. Topic should define the [issuance data format](/zerolabs-tokenization-module/domain-definitions/smart-contracts/certificate-registry/issuance-metadata.md).

Topics 0-10 are reserved for ZeroLabs, with the other topics available to be claimed by any other [issuer](/zerolabs-tokenization-module/domain-definitions/issuer.md) that wants to use the ZeroLabs [Certificate Registry](https://docs.zerolabs.green/zerolabs-tokenization-module/).

Examples for topic:

* 1 - ZeroLabs Token
* 2 - Renewable Energy Certificate by company X
* ...
* 10 - \<Available for anyone to claim> (open a [GitHub issue](https://github.com/zerolabsgreen/token/issues) and we will approve you as an issuer for that topic number)