43-EFT.WP.Data.DatasetCards v1.0 | Chapter 9 Metrology & Units

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Chapter 9 Metrology & Units

I. Chapter Purpose & Scope

II. Terminology & Dependencies

• Terminology source: General terms follow EFT.WP.Core.Terms v1.0; this chapter only adds metrology-related fields and constraints.
• Dependent volumes: Dimensional checks & uncertainty: Core.Metrology v1.0; equivalent expressions for arrival-time/path-dependent quantities: Core.Equations v1.1; data contract/export anchors and version-carrying: Core.DataSpec v1.0.

III. Metrology Baseline (Normative)

metrology:

units: "SI" # System-wide SI

c_ref: 299792458 # m/s

time_standard: "UTC" # UTC | TAI | GPS (UTC is public default)

freq_standard: "Hz"

angle_unit: "deg" # deg | rad (algorithms may use rad; public default deg)

length_unit: "m"

power_unit: "W"

energy_unit: "J"

flux_density_unit: "Jy" # if applicable to radio data

check_dim: true # enforce dimensional checks

rounding_policy: "bankers" # round-half-to-even

sigfigs_default: 3 # default significant figures

locale_decimal: "." # '.' as decimal separator

(metrology is a required object; its minimal keys are defined in Chapter 4; this chapter refines posture and extensions.)

IV. Dimensional Consistency & Checking Workflow

• Dimensional declaration: Numeric fields specify units in Schema or field tables; composite quantities use base dimensions M L T I Θ N J.
• Checking rules: With check_dim=true, all exports must pass dimensional conservation and unit consistency before release; failure is a blocking issue.
• Constants & references: Do not use bare c; use c_ref. Do not use bare n or T; use n_eff, T_arr/T_fil/T_trans with explicit meanings.

V. Arrival Time T_arr Metrology (Path-Dependent)

1. Two equivalent expressions:
   • T_arr = ( 1 / c_ref ) * ( ∫ n_eff d ell )
   • T_arr = ( ∫ ( n_eff / c_ref ) d ell )
2. Registration requirements: Whenever T_arr appears, register in the card: delta_form, path="gamma(ell)", measure="d ell", and pass check_dim.

VI. Time, Frequency & Spatial Coordinate Postures

• Time standards: Public default is UTC; if acquisition/processing uses TAI/GPS, record in provenance and provide the conversion and uncertainty aggregation (to uncertainty).
• Timestamp format: ISO 8601 (YYYY-MM-DDTHH:MM:SS.sssZ); time ranges use explicit half-open/closed notation (e.g., [t0, t1)).
• Frequency & sampling: Sampling frequency f_samp in Hz; bandwidth bw_hz in Hz; resampling must state anti-alias filtering and interpolation method.
• Spatial coordinates: Public default angle is deg; equatorial coordinates must specify epoch (e.g., J2000); maps/geodata must declare CRS (e.g., EPSG:4326).

VII. Units & Dimensions (Common Physical Quantities)

(Symbols use backticks; any division/integral/composite operator must use parentheses; no Chinese in formulas.)

VIII. Unit Conversion & Presentation

• Conversion policy: Public reports use SI; if industry units are used (e.g., Jy, eV), give SI equivalence at first use and maintain consistency.
• Rounding & significant figures: Default sigfigs_default; present statistics (mean/CI) with consistent significant figures; avoid “false precision.”
• Scalars/Vectors/Tensors: Declare units once at the field definition for vectors/tensors, not per component; axis units live with axes.

IX. Coupling with Uncertainty

X. Machine-Readable Fragment (Drop-in)

metrology:

units: "SI"

c_ref: 299792458

time_standard: "UTC"

angle_unit: "deg"

check_dim: true

rounding_policy: "bankers"

sigfigs_default: 3

path_dependence:

applies_to: ["T_arr"]

delta_form: "const-factor" # or "general"

path: "gamma(ell)"

measure: "d ell"

see:

- "EFT.WP.Core.Equations v1.1:S20-1"

- "EFT.WP.Core.Metrology v1.0:check_dim"

(see[] syntax aligns with export_manifest.references[], carrying Volume+Version+Anchor.)

XI. Coupling with Export Manifest

export_manifest:

references:

- "EFT.WP.Core.DataSpec v1.0:EXPORT"

- "EFT.WP.Core.Metrology v1.0:check_dim"

- "EFT.WP.Core.Equations v1.1:S20-1"

(All metrology postures must appear in export references; no shortcodes/aliases; version and anchor required.)

XII. Chapter Compliance Checklist

• metrology.units="SI", check_dim=true, export checks pass; c_ref and time/frequency/angle baselines declared.
• Any T_arr registers delta_form, path, measure, and validates against one of the two equivalent expressions.
• No Chinese in formulas; symbols wrapped in backticks; any division/integral/composite operator uses parentheses.
• Unit conversions, significant figures, and rounding follow this chapter; public materials cite stabilized lines with “Volume+Version+Anchor.”