Before mining begins, a miner chooses what to write into the block header's 64-byte nNonce field — a sentence, a melody, a record of something that happened. The choice happens first. Mining searches afterward, starting from it.
A block header carries several fixed pieces of information: a hash of the previous block (32 bytes), a hash summarizing the current block's transactions (32 bytes), a timestamp (4 bytes). Of all of it, nNonce — 64 bytes, indexed nonce[0] through nonce[63] — is the one part a miner is free to fill with chosen content. The rest is determined by the chain itself.
Each of the 64 bytes holds a value 0–255. Taken together they give 2⁵¹² possible values — finite, but for any practical purpose, inexhaustible.
Mining starts at nonce[0] and counts upward — when a byte passes 255 it resets to 0 and the next byte up increases. By the time a valid hash is found, usually no more than the last 1–2 bytes have changed. Content is written in the opposite direction: its end sits near nonce[0], where drift happens; its beginning sits near nonce[63], which mining essentially never reaches.
The value held in nonce[63] selects how the field is interpreted. A miner chooses this before the search begins — and it's the only choice that shapes how every other byte is read.
The whole field, including nonce[63] itself, is read directly — text, music, or both, byte by byte.
The remaining 63 bytes are read as UTF-8 text — any human script, not only Latin. nonce[63] itself holds no content.
The remaining 63 bytes are read as 126 four-bit nibbles — twice the notes of base mode, nothing but music.
Reading this field is direct correspondence, not computation — each byte maps to exactly one meaning, nothing derived or transformed along the way.
| Byte | Meaning |
|---|---|
| 0 | Rest (in music) / terminator (at the end) |
| 1 – 7 | Notes: C · D · E · F · G · A · B |
| 8 – 12 | Octave: low · mid-low · middle · mid-high · high |
| 13 – 17 | Duration: whole · half · quarter · eighth · sixteenth |
| 18 – 22 | Dynamics: pp · p · mf · f · ff |
| 23 | Sharp (♯) — applies to the next note |
| 24 | Flat (♭) — applies to the next note |
| 25 – 29 | Tempo: Largo · Andante · Moderato · Allegro · Presto |
| 30 | Dot — multiplies the current duration by 1.5 |
| 31 | Separator — clears any pending modifier |
| 32 – 126 | Printable text — ordinary letters, numbers, punctuation |
| 127 | Line break |
State bytes (8–29) stay in effect until replaced by another of the same kind. Modifiers (23, 24, 30) apply once, to whichever note comes next, then clear. Byte 31 clears any pending modifier immediately, even unused.
Middle octave · quarter note · mf · Moderato. Every unset field falls back to one of these until a miner chooses otherwise.
The first content ever written on-chain filled the field exactly: 64 characters, no punctuation, all 64 bytes used.
bit is found in memory It is the result of time and intelligence
Reading it backward — last character first, first character last — and writing each character's keyboard code as a byte gives the value placed into the field before mining begins:
The result of mining it:
Only the first byte or two changed. Decoded back:
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the last two characters drifted — "ce" became "e<". the rest of the sentence remains exactly as written.
Any human script — not only Latin — fills the remaining 63 bytes directly. A zero-value byte marks the end of content if one is present; content may also fill all 63 bytes with no marker at all. If drift corrupts the final byte or two, that part decodes as a generic placeholder character rather than failing outright.
The remaining 63 bytes are read as 126 four-bit nibbles — an upper and lower half per byte. Nibble 0 is the upper half of nonce[62]; nibble 125 is the lower half of nonce[0]. Half the range per nibble, but twice as many of them: far more notes than base mode allows.
| Nibble | Meaning |
|---|---|
| 0 | Rest |
| 1 – 7 | Notes: C · D · E · F · G · A · B |
| 8 | Escape — the next nibble is a control selector |
| 9 | Inline: middle octave (restores default) |
| 10 | Inline: quarter note (restores default) |
| 11 | Inline: eighth note |
| 12 | Inline: half note |
| 13 | Inline: high octave |
| 14 | Inline: low octave |
| 15 | Inline: mf dynamics (restores default) |
after escape (8) — selector: 0 end of stream · 1 sharp · 2 flat · 3 dot · 4 set octave (+1 nibble, 0–4) · 5 set duration (+1 nibble, 0–4) · 6 set dynamics (+1 nibble, 0–4) · 7 set tempo (+1 nibble, 0–4) · 8 separator · 9 line break · 10 natural · 11 tie · 12–15 reserved
Seven of sixteen nibble values act as one-nibble shortcuts for the state changes used most often; everything else goes through the escaped form above. Ending a stream takes two nibbles — escape, then end-of-stream — so a stream of exactly 125 nibbles has no room for both; one event must be added or removed instead.
nonce[63] values 130–255, and selectors 12–15 in packed music mode, are presently undefined. Leaving a value undefined costs nothing today and keeps tomorrow's question open — assigning it costs the freedom to decide differently, since anything already written under it depends on it staying what it was.
Beyond requiring mining to count upward from nonce[0], nothing restricts who writes into the field, what they write, or how the space is divided among a group. A group can share the same content and search independently, each across a non-overlapping range — whoever finds a valid hash first, the content belongs to all of them.
Most mined nonces carry no chosen content — just whatever value happened to satisfy the target. But because base mode assigns a meaning to every value 0–127, this works in reverse too: a nonce nobody composed can still be read through the same table, and some readings happen to hold together as a melody nobody wrote. People have searched mined nonces specifically for this — not to recover a choice, but to find sequences that happen to decode as something coherent, in a space too large for it to happen often.
Once mined, a deliberately written choice becomes part of the permanent block record. It does not depend on the person who wrote it, on any particular software, or on anyone remembering it exists. Decoding it requires only the chain itself and the byte map above — both of which persist independently of any single participant.