M4 or M-4 most often refers to: M4 carbine, an American carbine M4 Sherman, an American World War II medium tank M4, M04, or M-4 may also refer to: Arts and entertainment M4 (EP), a 2006 EP by
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 0xb9932559f698da56db90ad3b379f85ccaaa13e50358d5eaea8b2d10505382025. Chain 2 (Bitcoin): anchored in block 953407 (2026-06-12T19:24:56Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/59848080-6514-47ba-adb6-5b985f7b3012.json and https://artists.proofprofile.net/proofs/artist/59848080-6514-47ba-adb6-5b985f7b3012.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).