Friday is the day of the week between Thursday and Saturday. In countries adopting the "Monday-first" convention it is the fifth day of the week. In countries that adopt the "Sunday-first" convention,
1. Compute SHA-256 of OTSCanonicalRecord value → must equal OTSHash 2. Open OTSProofURL → extract Bitcoin block number → must equal OTSBitcoinBlock 3. GET OTSBitcoinBlockVerifyURL → returns the Bitcoin block hash at height OTSBitcoinBlock; GET https://blockstream.info/api/block/{that hash} → its timestamp must match OTSTimestamp 4. Read CopyrightID inside OTSCanonicalRecord → must equal the CopyrightID above 5. GET OTSVerificationAPI → pre-computed 6-check result from server 6. If all match: this entity was registered on CopyrightChains at OTSTimestamp, independently verifiable on Bitcoin
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x1a6f4afff1cb3dd6d560d42423df8aa86ffb7e91f8cefaf5c9843f9693be97ae. Chain 2 (Bitcoin): anchored in block 954010 (2026-06-16T21:41:36Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/3420be75-9915-47c3-b3d4-5a4dc3401d8b.json and https://artists.proofprofile.net/proofs/artist/3420be75-9915-47c3-b3d4-5a4dc3401d8b.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).