# Material-validation inputs

`din-67600-material-coefficients.csv` contains 260 material–illuminant pairs
and 520 weighted coefficients from DIN/TS 67600:2022-08, Tables 6 to 10.
It covers 71 materials: 12 glazing samples, 11 multi-skin sheets, 21 plastics
or filters, and 27 reflecting surfaces. The unglazed reference is excluded.

- `din_id`: material identifier printed in the DIN tables.
- `din_name_de`: original German designation, with line breaks removed.
- `din_name_en`: English editorial translation of that designation. It does
  not add TUB construction details.
- `group`: material family.
- `mode`: Transmission or Reflection. This determines whether the two
  coefficients are transmittance or reflectance.
- `illuminant`: evaluating illuminant as labelled in DIN. Transmission uses
  D65; reflection uses EE, A, D65, FL11, LED-B1, LED-B2, LED-B3 and LED-B5.
- `din_vis`: photopic material coefficient, a dimensionless fraction.
- `din_mel`: melanopic material coefficient, a dimensionless fraction. DIN
  also uses the designation k_mel for the weighted material factor under
  illuminants other than D65. This field is not MDER or effective MDER.
- `din_table_ref`: DIN table number.
- `page`: printed DIN page number, not the PDF viewer's page index.

Both numeric columns retain the published values to three decimal places.
Trailing zeroes need not be present in a machine-readable numeric field.
The CSV is UTF-8, comma-separated, with decimal points.

`tub-assignments.csv` separately records the 39 documented specimen
assignments used by the article: `din_id` and Spectran's `catalogue_id`.
These assignments are project metadata, not additional columns transcribed
from DIN. The article resolves TUB descriptions and source-column provenance
from the current Spectran catalogue. Unassigned materials remain in the DIN
CSV and are shown in one missing-spectrum table.

## Preparation

The article reads these CSV files directly. No PDF or extracted text is
required during rendering. To repeat the preparation from a local, licensed
copy of the standard, run from the Spectran package root:

```sh
pdftotext -layout /path/DINTS67600.PDF /path/DIN-TS-67600.txt
Rscript --vanilla data-raw/prepare_din_material_coefficients.R \
  /path/DIN-TS-67600.txt vignettes/articles/material-validation-data
```

The R script validates row identifiers, column counts, coefficient ranges and
unique material–illuminant pairs. Material descriptions are transcribed in
the script and English translations are recorded explicitly. Its output
`preparation-provenance.txt` records the source-text checksum, R version,
consequential package versions and command structure. The licensed source PDF
and its text extraction are not included here.