A data.frame containing five columns.
1. ID - A unique identifier for the bill.
2. cong - The session of congress that the bill first appeared in.
3. billnum - The number of the bill as it appears in the congressional docket.
4. h_or_sen - A field specifying whether the bill was introduced in the House (HR) or the Senate (S).
5. major - A manually labeled topic code corresponding to the subject of the bill.