Carolus Hacquart (the latinised form of his original name: Carel Hacquart) (c. 1640 - after 1686) was a Flemish composer and musician. He became one of the most important 17th-century composers in the
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 0x9f97f7c9a95ea86e7b0011ed0f78f94f0efd30c566ffd9aae4ce6a8039582571. Chain 2 (Bitcoin): anchored in block 954065 (2026-06-17T08:10:43Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/522f20e5-e5a4-4fcc-83dc-2c54c7d8ed67.json and https://artists.proofprofile.net/proofs/artist/522f20e5-e5a4-4fcc-83dc-2c54c7d8ed67.ots, the client at https://opentimestamps.org runs `ots verify -f record.json proof.ots`.
Sonata à 3 in D Minor, Op. 2 No. 6: I. Allegro
Chamber Music: London Baroque - Rosenmuller, J. / Hacquart, C. / Buxtehude, D. / Biber, H. I. F. (The Trio Sonata in 17Th Century Germany)
1. Confirm isrcCode identifies the recording in the pre-2022 source corpus and cc-db-prod record 2. GET OTSVerificationAPI → server-side canonical-record, hash, and attestation checks must pass 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. Confirm CopyrightID is the CopyrightChains transaction hash 5. If all match: the cc-db-prod record is independently anchored on Bitcoin at OTSTimestamp 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 0xdf4bc515e35391f0ffb3bc2336b5e5ea38233ac023a46d1c941cf48b9b7eae6a. Chain 2 (Bitcoin): anchored in block 960236 (2026-07-30T09:37:10Z), registered by our registry partner. The server verifies the private canonical record against OTSHash without exposing internal provider keys. Confirm the public ISRC, CopyrightID, and Bitcoin evidence at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/SEAEP0845140 — a six-check JSON result.
Sonata à 3 in D Minor, Op. 2 No. 6: III. Adagio
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x25f25960588ee6caccd2f81635699e17f499517efd3e6c6a741f2d628930e4d0. Chain 2 (Bitcoin): anchored in block 957118 (2026-07-08T03:20:19Z), registered by our registry partner. The server verifies the private canonical record against OTSHash without exposing internal provider keys. Confirm the public ISRC, CopyrightID, and Bitcoin evidence at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/SEAEP0845160 — a six-check JSON result.
Sonata à 3 in D Minor, Op. 2 No. 6: VI. Canzona. Vivace - Adagio
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xb9ea514e2abfb80488b96d376442153119aee7314515a8fda34d256dc9baaf31. Chain 2 (Bitcoin): anchored in block 960220 (2026-07-30T07:28:30Z), registered by our registry partner. The server verifies the private canonical record against OTSHash without exposing internal provider keys. Confirm the public ISRC, CopyrightID, and Bitcoin evidence at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/SEAEP0845190 — a six-check JSON result.
Sonata à 3 in D Minor, Op. 2 No. 6: II. Adagio
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xd9ba5be2acf383c85a83285bbaa2f9d16f7b3e5e7c39f86bcc86f6ff1c258c67. Chain 2 (Bitcoin): anchored in block 960321 (2026-07-30T22:27:30Z), registered by our registry partner. The server verifies the private canonical record against OTSHash without exposing internal provider keys. Confirm the public ISRC, CopyrightID, and Bitcoin evidence at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/SEAEP0845150 — a six-check JSON result.
Sonata à 3 in D Minor, Op. 2 No. 6: IV. Adagio
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x391ecce79e6b7ac327aac540e14c417d7198c81d497caf98e8c55d2871fff9e6. Chain 2 (Bitcoin): anchored in block 957118 (2026-07-08T03:20:19Z), registered by our registry partner. The server verifies the private canonical record against OTSHash without exposing internal provider keys. Confirm the public ISRC, CopyrightID, and Bitcoin evidence at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/SEAEP0845170 — a six-check JSON result.
Sonata à 3 in D Minor, Op. 2 No. 6: V. Grave - Allegro
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xf74ddc239d0545b73ae0e6eeb9c54bd98c189c4c764ba3d26890bee3487e3d9d. Chain 2 (Bitcoin): anchored in block 957120 (2026-07-08T03:22:41Z), registered by our registry partner. The server verifies the private canonical record against OTSHash without exposing internal provider keys. Confirm the public ISRC, CopyrightID, and Bitcoin evidence at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/SEAEP0845180 — a six-check JSON result.
Sonata à 3 in D Minor, Op. 2 No. 6: VII. Aria. Vivace
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x4e9f2f5d87b5f9be5ba60d0dc49b8c6e8b74ac4f6d26e331af97b14aff300fc2. Chain 2 (Bitcoin): anchored in block 960291 (2026-07-30T18:23:33Z), registered by our registry partner. The server verifies the private canonical record against OTSHash without exposing internal provider keys. Confirm the public ISRC, CopyrightID, and Bitcoin evidence at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/SEAEP0845200 — a six-check JSON result.