Ligt as a Conserved Transport Content in QMU: A Knob Manual for Engineering and Measuring Light in the Aether Physics Model

Overview.This paper is a practical engineering and metrology manual for treating light as a conserved transport content in Quantum Measurement Units (QMU) within the Aether Physics Model (APM). The central quantity is ligt, and the core methodological claim is that many distinct laboratory interfaces (``knobs'') are not separate physics, but ledger-closed factorizations of the same conserved transport content. Each factorization tells you (i) what an apparatus truly controls, (ii) what it truly measures, and (iii) which invariant must hold if the intended regime is actually being realized. Core definition (ledger-closed).The conserved light transport content is defined by the canonical QMU closure$$\mathrm{ligt} \;:=\; m_e\,{\lambda_C}^{3}\,{F_q}^{3},$$with the chronovibrational identity$$c = F_q\,\lambda_C\qquad\Rightarrow\qquad\mathrm{ligt} = m_e\,c^3.$$As an SI bridge only (for comparison with radiometric bookkeeping), $\mathrm{ligt}$ has dimensions of $\mathrm{W\cdot m}$ and numerically$$\mathrm{ligt} \approx 2.4544\times 10^{-5}\ \mathrm{W\cdot m}.$$ What the manual provides.The paper supplies: A one-page decision tree / knob map that routes a real apparatus to the first card(s) to use (radiometric transport, resonance/rate control, opto-mechanical coupling, or magnetic-charge electromagnetic coupling). Three metrology rules that keep results interpretable: (M1) always write $2\pi$ explicitly when using $\omega=2\pi\nu$; (M2) declare charge basis explicitly (electrostatic $e^2$ vs magnetic ${e_\mathrm{emax}}^2$); (M3) use invariants as regime tests rather than curve-fitting targets. A complete set of 25 "ligt cards" (ledger-closed factorizations). Every card includes: (i) the closure identity, (ii) the knob (what can be controlled), (iii) what to measure, (iv) an invariant-to-check that validates the assumed regime. Diagnostic protocols: one minimal experiment per knob, with escalation guidance when invariants fail (treat failures as measurements indicating coupling migration or mode-structure changes). A worked photoemission-oriented example showing how to keep transport fixed (baseline cards) while diagnosing receiver-side gate changes (threshold/landmark migration) without changing transported content. Design philosophy: invariants are the instrument.In this framework, a failed invariant is not "noise" to be averaged away; it is a measurement indicating that the apparatus has changed the coupling family (geometry, mode structure, surface participation, gating, or basis coupling). The manual is written to turn those failures into structured diagnostics. Supplementary machine-readable catalog.A companion JSON unit catalog (QMU_Units.json) is provided to support automated unit lookup, consistency checking, and software tooling. Each record includes the unit key, name, functional description, and (when applicable) ledger expressions in QMU primitives. Related program papers (DOIs).Transport geometry and baseline radiometric budgeting are consistent with: Cardioid Photon Expansion and the Inverse-Square Law in QMU. DOI: 10.5281/zenodo.18396383 Receiver-side photoemission gate interpretation is consistent with: Coherence-Window Quantization in Photoemission: Dual Electrostatic and Magnetic Gate Laws in QMU. DOI: 10.5281/zenodo.18395399 Aether-Unit Mechanism for the Photoelectric Effect (QMU/QADI). DOI: 10.5281/zenodo.18392964 Charge-basis conversion and magnetic-charge benchmarking are consistent with: The Charge Conversion Factor in the Aether Physics Model. DOI: 10.5281/zenodo.17451188