This foundational treatise provides a rigorous, self-contained axiomatic exposition of the Principia Metrica Framework (PMF). Designed as a comprehensive mathematical and notation reference, this work establishes the exact functional-analytic, differential-geometric, and algebraic architecture underlying recent resolutions across number theory, non-linear partial differential equations, quantum field theory, computational complexity, and algebraic topology. We formulate the universal state space as the infinite-dimensional real Clifford algebra Cl(∞, 0) ≅ varinjlim Cl(n, 0) endowed with a strict locally convex inductive limit topology, its L²-Hilbert space completion H(PMF), and a Gel'fand triple structure Φ ⊂ H(PMF) ⊂ Φ*. We detail the embedding of the isotropic horosphere H² ⊂ ℝ⁽∞⁺¹,¹⁾ (the Dupin horn cyclide), the Kähler–Atiyah deformation quantization connection ★(ħ), the irrational Lie rotor flows driven by θ = log₂(3) ∉ ℚ, and the Nilpotent Horizon volume ceiling V(cap) = ζ(6) = π⁶/945. Finally, we provide a Bourbaki/AMS translation dictionary and prove the Projection Theorem, establishing how classical vectors, tensors, and 1D real coordinate lines emerge as low-grade projection shadows π₃,₁.