How do I page and filter dataset content (range, keys, JSON versus RAW)?

POST or GET /dataset-content with limit/skip, or range (1-based; range ignores skip/limit), or keyedPagination on unique-key KSDS. responseFormat RAW is a binary stream; JSON is records with id, position, and base64. Server-side filters need fields plus filterExpr. 409 means exclusive open by another process.