This technical paper describes the signbox as the spatial arrangement carried in Formal SignWriting text. It explains how symbols, coordinates, centering, tight bounding boxes, and normalization preserve visible composition while allowing signed text to work in software. The paper connects the writing-systems claim that SignWriting is spatially authored with the formal technical model needed for storage, validation, processing, and rendering. The Shape of a Sign provides the spatial layer of the Formal SignWriting model and the public handoff from plane-based writing theory into technical text infrastructure. This document DOI record includes the plane-writing technical bridge and technical notes as companion packet files for the technical paper.
Steve Slevinski (2026) studied this question.