XZ, X.Z., or xz may refer to: Transportation AeroItalia (IATA code: XZ), an Italian airline South African Express SA Express (former IATA code: XZ), a former South African airline XZ, a type of PS
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 Note: an OTS proof may carry multiple Bitcoin attestations; OTSBitcoinBlock is the earliest confirmed one — a later attestation inside the proof corroborates it and is not a mismatch
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xcd9ba907c4a304590c49f7936cb3723b858c1a4b0c854846b905a44755a33605. Chain 2 (Bitcoin): anchored in block 953783 (2026-06-15T12:24:43Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/d64ec8aa-ba79-46f2-93f4-e69697dae3b0.json and https://artists.proofprofile.net/proofs/artist/d64ec8aa-ba79-46f2-93f4-e69697dae3b0.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).