> ## Documentation Index
> Fetch the complete documentation index at: https://www.plain.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# upsertAccountFieldSchema

> Creates or updates one or more account field schemas in a single call. Each schema is identified by the combination of `source` and `externalFieldId` — if a schema with that pair already exists it is updated, otherwise a new one is created. Requires the `tenantFieldSchema:create`, `tenantFieldSchema:update`, and `tenantFieldSchema:delete` permissions.



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