What question did this study set out to answer?

To establish the SFT-5 framework, which categorizes visible structural flow patterns for observation purposes.

June 19, 2026Open Access

SFT-5 Public Definition Canon v0.1: A Five-Type Structural Silhouette Flow Framework for Visible-Body Observation

Key Points

To establish the SFT-5 framework, which categorizes visible structural flow patterns for observation purposes.
Defines five active structural silhouette types: Y-Line, A-Line, X-Line, O-Line, Z-Line.
Distinguishes between Primary and Secondary types based on observed structural flows under various conditions.
Defines Review State categories for governance in classification.
Introduced five distinct types for describing visible body structural flows without imposing grades or health levels.
Clarified the interpretation boundaries and principles of SFT-5, emphasizing non-forced classification.
Encouraged public dialogue and contributions to foster scholarly engagement on the framework.

Abstract

This record publicly defines SFT-5, the Five-Type Structural Silhouette Flow Framework, as a typological language for describing dominant visible structural-flow patterns under a defined observation condition. SFT-5 contains five active public types: Y-Line — upper-frame and waist-transition flow A-Line — lower-frame and pelvis-centered flow X-Line — bidirectional convergence and curve continuity O-Line — central density and trunk-centered organization Z-Line — sagittal offset and rib–pelvis organization The five types are not grades, health levels, aesthetic ranks, diagnostic categories, or permanent skeletal identities. They describe different forms of visible structural emphasis and directional organization observed under the current condition. SFT-5 distinguishes the Primary Type, representing the most dominant currently observed structural flow, from a Secondary Tendency, representing an additional meaningful flow under mixed, transitional, boundary, or multi-view conditions. The framework also separates type from Confidence, Stability, Mode Context, Priority Mapping, and Review State. Review State is defined as an operational governance state rather than a sixth SFT type. When the available input does not support a sufficiently clear classification, the result should not be forced into the nearest category. Public review states may include Indeterminate, Retake Required, Human Review Required, Temporal Validation Required, and Unsupported Mode. SFT-5 is categorically descriptive but dynamically interpreted. Type does not determine Grade, and no SFT-5 type is inherently superior, healthier, more attractive, or more desirable than another. The framework does not replace continuous anthropometric records, BPI-R6 relational profiles, clinical assessment, or contextual human review. This record establishes the public identity, official five-type terminology, descriptive meaning of Y-Line, A-Line, X-Line, O-Line, and Z-Line, Primary Type and Secondary Tendency structure, Confidence and Stability concepts, Type–Grade Firewall, non-forced classification principle, Review State governance, and interpretation boundaries of SFT-5. The adjacent BPI-R6 public records are: Kang S. BPI-R6 Public Technical Definition v0.1: A Six-Coordinate Relational Profile for Visible Body-Proportion Representation. Zenodo. 2026. doi:10.5281/zenodo.20731035 Kang S. BPI-R6 Reference Concordance Framework v0.1: A Reference-Relative Six-Coordinate Representation for Visible Body-Proportion Profiles. Zenodo. 2026. doi:10.5281/zenodo.20731442 Kang S. BPI-R6 Dual-View Representation Architecture v0.1: A Linked Reference-Neutral and Reference-Relative Representation for Visible Body-Proportion Profiles. Zenodo. 2026. doi:10.5281/zenodo.20731854 SFT-5 remains a distinct typological framework and is not defined as a direct transformation of BPI-R6. No new empirical dataset is introduced in this record. Invitation for Scholarly Dialogue Questions, brief comments, critical perspectives, and informal scholarly conversations are all welcome. Researchers and practitioners who find any part of this work relevant to their own interests are warmly invited to contact the author. You do not need to have read the entire framework, developed a formal position, or prepared a collaboration proposal. Partial impressions, preliminary questions, and brief messages are equally welcome. Contact: Sarang KangEmail: corsetmuscle@gmail.com Keywords: Human Aesthetic Engineering; HAE; visible human form; visible-body interpretation; intersection framework; cross-domain coordination; domain-specialized framework; anthropometry; body scanning; computer vision; sports science; Human–Computer Interaction; Human–Data Interaction; human–machine systems; digital health; personal informatics; technological representation; reference selection; relational organization; contextual interpretation; longitudinal interpretation; interpretation boundaries; evidence-limited inference; responsible interpretation; BPI-R6; Body Proportion Index; body proportion; visible body shape; relational measurement; six-coordinate profile; multidimensional representation; body-data representation Version:v1.1.0 — Public Concept Note / Working Paper

Read Full Paperexternally

Bookmark

View Full Paper

Cite This Study

Sarang Kang (Fri,) studied this question.

synapsesocial.com/papers/6a34dec865a5b0777af2e1a8 https://doi.org/https://doi.org/10.5281/zenodo.20734237

Also Consider

Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context:

Bookmark

View Full Paper