The Alexander String Quartet is a string quartet based in San Francisco. Formed in New York in 1981, the Alexander String Quartet has since 1989 been Ensemble in Residence of San Francisco Performance
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 0x21d3c033dcdbc10623397543a892551941c73472a3a71c4b5a407a52e43e5625. Chain 2 (Bitcoin): anchored in block 953699 (2026-06-14T22:00:24Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/5c55063c-639e-4015-8cf1-5877d72a7810.json and https://artists.proofprofile.net/proofs/artist/5c55063c-639e-4015-8cf1-5877d72a7810.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).
String Quartet No. 20 in D Major, K. 499 "Hoffmeister": I. Allegretto
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
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xd1b23e406f0618863196b7a4fadf0329bd238d9d6d2d8407344d1ee329fb4e4f. Chain 2 (Bitcoin): anchored in block 957124 (2026-07-08T03:53:27Z), 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 via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/USB8U1800655.
String Quartet No. 20 in D Major, K. 499 "Hoffmeister": II. Menuetto
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xacb2e377bcc26a61d63d1c211523fc8a122a49fe01e0388d73a146241cc62405. Chain 2 (Bitcoin): anchored in block 960430 (2026-07-31T16:09:41Z), 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 via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/USB8U1800656.
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
Piano Quartet No. 2 in E-Flat Major, K. 493: III. Allegretto
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x31f11657b96ca1a29ee87674db992654c8bbeeb58cbaae043bc2e672536b070a. Chain 2 (Bitcoin): anchored in block 957124 (2026-07-08T03:53:27Z), 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 via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/USB8U1709425.
Bartók & Kodály: The Complete String Quartets
Chopin: Piano Concerto No. 2 F-Minor Op. 21 (Original Chamber Version) / Beethoven: Piano Quartet No. 3 C-Major WoO 36
Hamel: String Quartet No. 3, String Quartet No. 4, String Trio
Mozart: Homage - The Six Quartets Dedicated To Haydn
Beethoven: String Quartets Vol. 2 / Op. 18/2 And Op. 18/6