Settings › Schemas defines the shape of documents.
A schema is a list of fields — key, kind (text, rich text, number, date, image, file, reference, link, element, enum, list, group, …), validation, whether the field is per locale or shared, predefined values, hidden fields — plus flags for the built-in SEO container and the status picker (with the default status a new document starts with — public unless the schema says otherwise). A link field holds either a free URL or a pointer at one of the project's pages; the site resolves the pointer to that page's public address in the visitor's language, so renaming a slug never breaks a button or menu item. A schema's type is template (documents may render web pages — the editor offers the template versions and the live preview), data (the same document shape for content that renders no page, such as settings or lookup tables — no template chip, no preview) or enum (a reusable picklist). Collections point at a shared schema; a single document can also carry its own per-document schema (general/{collection}/{document}) for one-off pages.
The lock in the schema header freezes a schema's structure: in the document editor its documents then only take values — fields cannot be added, removed, renamed or reordered, by an editor or by the document assistant. The schema itself stays editable here. A locked shared schema also freezes the documents that extend it.
Enum schemas are reusable picklists other schemas reference. The built-in product base can be extended, not replaced: its locked fields stay.
Changing a schema changes the editor immediately; templates that bind to removed fields simply render nothing for them. The schema-builder agent (in the assistant column) can create and evolve schemas in conversation; the MCP writeSchema tool does the same for external agents — including the lock (locked: true / false).
Manager-only.