A letter, in the sense that matters for the tape, is not a private note. It is a mark that can be detached from its first writing and still function. Derrida’s account of the letter (in relation to the postcard, the signature, and destinerrance) stresses that a message which could not survive its sending would not be a message later readers could open. The condition of its force is that it can arrive elsewhere, in another context, after the one who wrote it is no longer present.

The public tape is a system of such letters. Title, mint, lien, and conversion can be sent. They continue after their authors have moved on. The Third Seat’s refusal is one such letter. The no can leave the room in which it was written. It stays on the record. Later readers can open it. They were not required to be its original recipients.

The quiet print claims the force of a letter without having become sendable. It is treated as already delivered. It cannot be detached and re-read. The speculative chart performs the same claim with the end. It offers a final letter that the unfinished middle has already received. The letter has not entered the tape. The public book refuses both. A mark that cannot be sent has not yet become a letter the others can still open.

Detachability. The mark must be able to leave its first scene and still function.

Arrival elsewhere. Later readers, in other contexts, must be able to open the line.

No private delivery. An office cannot treat an unshown claim as a letter that has already arrived.