PartnerReferenceAttribute

Attribute key. Stored keys:

• price_unit (required): kg, box, piece or pallet
• sale_unit: kg, box, piece or pallet; defaults to box
• numeric: vat_rate, net_weight (per-piece weight in kg, distinct from the LU-level box_weight)
• text: origin, ean13, brand, packaging, size_label, production_zone, tag

Any other key (e.g. variety, size, unit_measure_code) is accepted but not stored. A non-numeric value for a numeric key, or a unit outside the list, rejects the row. On update, the list replaces the stored attributes.

Attribute value. May be sent as either string ("5.5") or number (5.5); the server accepts both. Attributes whose value is empty or null are skipped.