The True Understanding Invariant Structural Framework (TU-ISF) develops a more formally structured account of the relationships introduced conceptually in the Conceptual Model of Understanding (CMU). Where CMU describes understanding as the emergence of coherence from uncertainty, TU-ISF explores the invariant structural relations that may govern how possibility becomes constrained, how coherence stabilises, how actualisation produces consequence, and how irreversible consequence reshapes future conditions. The framework is intentionally regime-local. It does not assume universal applicability across all domains, scales, or contexts. Nor does it propose replacement mathematics, replacement physics, or a completed explanatory system. Instead, it provides a disciplined structural language for describing recurring relations among possibility, contextual constraint, actualisation, and consequence. Central concepts include admissibility, contextual constraint, actualisation, and Recursive Trace (RT). Together, these concepts form a framework for examining how consequence accumulates, how future possibilities become reshaped, and how coherence remains conditioned by context. TU-ISF functions as the formal structural expression within the wider True Understanding ecosystem. It provides a bridge between the conceptual foundations of CMU and the later scientific, technological, human, and educational expressions of the framework.