> For the complete documentation index, see [llms.txt](https://guardian.hedera.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://guardian.hedera.com/docs/develop/guardian/workspace/schemas/schema-types.md). # Schema Types Understand the five schema types used in Guardian. Schemas define the structure of data used in Guardian. They keep policy data consistent and machine-readable. Guardian organizes schemas by their owning context. Five schema types support policies, tools, modules, tags, and platform services. #### The problem it solves Without schema types, data ownership becomes unclear. Reusable components could require incompatible data structures. #### How it works Each schema type defines where its data is used. Guardian applies that structure across policies and reusable components. * **Policy schemas:** Policy schemas define data used by a policy. They structure documents and credentials within its workflow. A policy can include multiple schemas. Each schema supports a specific workflow or data requirement. * **Tool schemas:** Tool schemas are embedded in tools. They structure documents and credentials used by the tool. A policy can use tool schemas when it includes the tool. This keeps shared workflows consistent. * **Module schemas:** Module schemas define data required by reusable modules. A module exposes schema requirements through variables with the `schema` type. The selected schema provides the module's base data structure. This keeps module inputs consistent across policies. * **Tag schemas:** Tag schemas define documents attached to tags. A tag requires a schema before it can collect structured document data. Use tag schemas when metadata must accompany a tag. See [Schema Tags](/docs/develop/guardian/workspace/schemas/tag-schema.md) for details. * **System schemas** Guardian creates system schemas automatically when an account is created. They support core platform entities and workflows. System schemas are read-only by default. They cannot be edited or deleted. #### Key distinctions Policy schemas belong directly to a policy. Tool and module schemas belong to reusable components. Tag schemas support tag metadata. System schemas support Guardian's core platform behavior. #### Related * Task: [Creating a Schema](/docs/develop/guardian/workspace/schemas/create-schema.md) * Guide: [Schema Design Best Practices](/docs/develop/guardian/workspace/schemas/best-practices-to-implement-schema.md) * Guide: [Managing Schemas with Excel](/docs/develop/guardian/workspace/schemas/import-and-export-excel-file-user-guide.md) --- # 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 by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://guardian.hedera.com/docs/develop/guardian/workspace/schemas/schema-types.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. 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.