The problem with this is that I'm not sure that the person reading it will definitely know what an action function is. Also I don't think it's true that every action function uses a schema. I think just make it slightly more specific to IDatasetForm, something like "When a dataset is created, viewed or updated the parameters passed to CKAN (e.g. via the web form when creating or updating a dataset, or posted to an API endpoint) are validated by a schema."