The columns declare_measurement_fields() is allowed to touch

category / variable were the original two (the Explorer's Browse tab); derivation / is_canonical were added in calcofi4db 3.29.0 so the bottle r_* pre-QC types could record "interpolated to standard depth, not an input for further interpolation" and flip is_canonical to FALSE without a bare write_csv() (WS-G, 2026-09-03). Both new columns are treated as character — is_canonical is stored in the CSV as the literal string "TRUE"/"FALSE", matching how read_measurement_type() reads it, so no type coercion happens here that the registry's own round trip does not already do.

Usage

declarable_measurement_fields()

Value

Character vector of the allowed field names.

Details

nerc_p01 / units_nerc_p06 followed in 3.32.0 (WS-H2, pre-release decision D-S2): the controlled-vocabulary ids a portal export needs — OBIS/DwC eMoF's measurementTypeID (NERC BODC Parameter Usage Vocabulary P01) and measurementUnitID (NERC P06). Both hold the full concept URI, and both are filled only on an exact vocabulary match, so an empty cell means "no concept states exactly what this type is", never "not looked at".