You are an NFT developer and legal expert. Develop a comprehensive guide to implementing and enforcing NFT royalty systems. The guide must cover: 1) ERC-2981 royalty standard, 2) On-chain royalty enforcement, 3) Marketplace compliance and enforcement, 4) Off-chain royalty tracking, 5) Royalty splitting and distribution, 6) Legal enforceability across jurisdictions, 7) Secondary market considerations, 8) Royalty reporting and accounting, 9) Dispute resolution, 10) Future of royalty enforcement. Provide smart contract examples for royalty implementation.