Toward a Metrology of Viability Boundary Dynamics: Operationalization, Measurement, and Reproducible Testing of VBDP

This article develops the candidate Theory of Viability Boundary Dynamics proposed in G17 and formulates the metrological stage of its testing. If G16 addressed the question “Where can the system remain viable?” and G17 asked “How does the system move relative to the boundary, and can approaching loss of viability be detected?”, G18 asks: How can position, motion, recovery, feedback, and reserve be measured in such a way that the resulting observations can be tested, compared, and reproduced? The external metrological foundation includes the International Vocabulary of Metrology (VIM), the Guide to the Expression of Uncertainty in Measurement (GUM), and JCGM documents concerning measurement models and conformity assessment. International metrological terminology requires distinction between a measurand and the general object under study, and between a measurement result and a single numerical value without information concerning uncertainty. Metrological traceability connects a result to a documented chain of references, while traceability alone does not guarantee that the resulting uncertainty is adequate for a specific decision problem (JCGM, 2008; JCGM, 2012a; JCGM, 2012b; JCGM, 2020). G18 proposes a metrological architecture for the following components: M_V — boundary margin; A_B — boundary approach rate; T_R and RDP — recovery time and recovery dynamics profile; FEP — Feedback Effectiveness Profile; R_rob — dynamic robustness reserve; R_reg — regenerative reserve; R_ad — adaptive reserve. Particular attention is given to the distinction between actual system variability and measurement error, temporal resolution, uncertainty of derivative quantities, standardization of perturbations, predefined classification rules, prospective prediction, comparison with baseline models, and independent reproducibility. The article proposes several working constructs: Viability Boundary Dynamics Measurement Specification, Standardized Perturbation Protocol, VBDP Uncertainty Profile, Boundary Decision Interval, Prospective Viability Boundary Dynamics Test, and VBDP Reproducibility Matrix. The central methodological distinction of G18 is: Theoretical Determinacy ≠ Metrological Determinacy. And: Measurability ≠ Validity ≠ Predictive Added Value. The scientific status of VBDP can increase only if its components are independently operationalized, their uncertainty is evaluated, the measurements are reproducible, and the multidimensional profile demonstrates an advantage over simpler disciplinary models on new data. Keywords: Vitology; viability; metrology; viability domain; viability boundary dynamics; VBDP; measurand; operationalization; measurement uncertainty; metrological traceability; reproducibility; repeatability; recovery; feedback; reserve; standardized perturbation; prospective testing; predictive diagnostics; baseline model.