For parse/split/extract pipelines, the URL of the document to be processed. You can provide one of the following:
1. A publicly available URL
2. A presigned S3 URL
3. A reducto:// prefixed URL obtained from the /upload endpoint after directly uploading a document
4. A jobid:// prefixed URL obtained from a previous /parse invocation
5. A list of URLs (for multi-document pipelines, V3 API only)
For edit pipelines, this should be a string containing the edit instructions