Parts and accessories of computing machines

1. Scope and Applicability

This PCR supports foreground data packages for separately supplied computing-machine parts that do not themselves perform the function of a complete computer. The implemented routes are mechanical completion of a supplied steel chassis shell and acceptance testing of a supplied populated motherboard without CPU and BIOS ROM. These are separate product models, not co-products. The representative part is a bare steel chassis. The official classification distinguishes parts from computing machines, storage units and expansion cards (un-cpc-3-0-structure-2025); the two CBP rulings substantiate concrete chassis and incomplete-motherboard boundary examples (cbp-n304809-2019, cbp-n025223-2008). Their historic tariff rates and trade-agreement conclusions are not adopted.

This is an explicitly bounded final-assembly, testing and packing foreground model. Supplier fabrication, semiconductor production, PCB population, metal forming and surface treatment remain in upstream datasets; they are not burden-free exclusions. A site performing those operations must supply additional measured unit-process inventories before claiming complete coverage. Do not apply the twelve-row starting inventory unchanged to a different bill of materials. Every extra physical exchange must have its own atomic row, identity and collection record.

2. Product Category Identity

Field	Value
canonical_pcr_id	pcr.metal-products-machinery-and-equipment.office-accounting-and-computing-machinery.parts-and-accessories-of-computing-machines
classification_refs	CPC 3.0 45290; classification identity source un-cpc-3-0-structure-2025
covered_products	Separately supplied computer chassis and incomplete motherboards; other solely or principally computing-machine parts require a declared product-specific inventory extension
excluded_products	Complete computers; functioning processing units; storage units; input/output peripherals; sound/video/network cards; bare printed circuits; integrated circuits sold separately; carrying cases; repair services
representative_product	Bare steel computer chassis, declared model and net mass
production_route	Supplied formed shell to mechanical completion, or supplied populated incomplete motherboard to acceptance testing; packing in both routes
market_state	New accepted part for OEM integration or replacement; no complete-computer function

3. Reference Flow

Field	Value
What	Supply a specified computing-machine part for mechanical enclosure or declared board interface function
How much	1 kg net accepted parts of one model; declare corresponding item count
How well	Meets the model drawing, mounting/interface requirements and documented acceptance test; unlike functions are not interchangeable
How long or cycle	One production and acceptance cycle to the factory gate; service life and host-computer use profile are not inferred
reference_flow_link	chassis_product is the representative output; a board-specific package uses motherboard_product as its sole reference and updates the concrete reference identity

Field	Value
Reference amount	1
Reference product flow	Steel computer chassis
Reference flow property	Mass 93a60a56-a3c8-11da-a746-0800200b9a66
Reference unit group	Units of mass 93a60a57-a4c8-11da-a746-0800200c9a66
Reference unit	kg
Required qualifiers	part model; part function; chassis or incomplete-board route; net mass per item; material composition; supplier starting state; CPU and BIOS presence; interface/drawing revision; acceptance test; production site; reporting period; packaging specification; upstream coverage; factory-gate boundary

Declare every qualifier in the data package. Reference mass is a normalization choice, not evidence of functional equivalence. A motherboard-specific package must replace the representative chassis identity and acceptance specification with its actual board identity. A board with CPU and BIOS that has the character of a processing unit requires a separate boundary review (cbp-n025223-2008).

4. Measurement and Unit Rules

rule_id	Applies to	Required property	Required unit	Rule
net_mass	Reference part and material reconciliation	Mass 93a60a56-a3c8-11da-a746-0800200b9a66	kg	Use accepted net product mass; exclude packaging. Record item count and measured model-specific mass per item; do not convert across models with a generic coefficient.
electrical_energy	Purchased electricity	Net calorific value 93a60a56-a3c8-11da-a746-0800200c9a66	MJ	Preserve metered energy; 1 kWh = 3.6 MJ is an exact unit identity. Declare voltage, supply mix, site and time coverage.
yield_basis	All exchanges	Mass 93a60a56-a3c8-11da-a746-0800200b9a66	kg	Divide batch exchanges by accepted net output of the same model and period; record rejects and rework separately so test failures remain burden-bearing.

5. System Boundary

rule_id	applies_to	rule	source_ids
gate_boundary	Product system	Use a disclosed cradle-to-gate intermediate-part inventory when the host use profile is unknown; include upstream supply, inbound logistics, assembly, testing, packaging and production-waste treatment. Exclude host use and host end of life together; disclose any separate downstream study.	ghg-protocol-product-standard-2011
supply_link	Purchased part inputs	Attach boundary-compatible upstream datasets to the supplied shell and populated board. An onsite activity cannot be hidden in a purchased-input label. Reconcile supplier and foreground coverage to prevent gaps or double counting.
test_boundary	Acceptance tests	Count test-fixture electricity and rework in production. Test fixtures temporarily supplying CPU or BIOS are not shipped product inputs; consumptive replacements require their own inventory rows.
extension_completeness	Additional operations	A real fuel, chemical, refrigerant loss, wastewater, incoming packaging waste or extra BOM component requires a separate measured atomic exchange. The representative dry finalization route assumes none without confirming site records.

Boundary Abstraction

Field	Value
declared_starting_condition	Supplier-produced formed and surface-finished chassis shell, or populated motherboard lacking CPU and BIOS ROM, awaiting final acceptance
starting_condition_role	Purchased intermediate; upstream fabrication remains linked background supply
product_classification_scope	Computing-machine parts; independently functioning machines and separately classified units remain outside this category
recursive_input_rule	Same-category input is recorded at its actual delivered state and linked once to a supplier dataset. Do not recursively instantiate this finishing process or count purchased and internally fabricated versions together.
upstream_dataset_requirement	Supply-specific cradle-to-delivery data covering raw materials, fabrication, yield, component manufacture and transport; if only factory-gate data exist, add inbound transport from actual shipment records
disclosure	Model, route, make/buy split, included tests, supplier coverage, transport endpoints, omitted exchanges with evidence and system-boundary limitations

6. Process Inventory Structure

Process Map

process_id	process_name	inclusion	inclusion_condition	role	quantitative_reference
chassis_completion	Chassis mechanical completion	conditional	The declared product is a steel computer chassis assembled from a supplied shell	foreground production	1 kg accepted net chassis
board_acceptance	Incomplete motherboard acceptance	conditional	The declared product is a supplied populated motherboard without CPU and BIOS ROM awaiting acceptance testing	foreground production	1 kg accepted net motherboard
packing	Packing	required	Applies to the selected part model; each packaging exchange requires evidence of use	foreground packing	1 kg accepted net part passing through packing

Choose exactly one part route. Packing is measured separately and preserves net part identity and mass; do not add a second reference-product output or duplicate the internal transfer. The supplied shell and board routes require the upstream datasets specified in section 5.

Process: Chassis mechanical completion (chassis_completion)

Inputs

Product flows

Chassis shell supplied for final assembly (chassis_shell)

Chassis route only; purchased shell incorporates the declared forming and surface treatment. Record receipt mass and supplier coverage.

• Selected flow: Formed steel computer chassis shell
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg; unit group 93a60a57-a4c8-11da-a746-0800200c9a66
• Amount rule: Collect the batch quantity in kg and divide by accepted net output mass for the same model and period; preserve raw records and route applicability.
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg accepted net part of one declared model
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_chassis_materials

Mechanical fastening (screw)

Include when steel screws are installed; reconcile issued mass, unused returns and retained mass.

• Selected flow: Steel screw 895204f6-6425-4814-afc5-cb97e530e892
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg; unit group 93a60a57-a4c8-11da-a746-0800200c9a66
• Amount rule: Collect the batch quantity in kg and divide by accepted net output mass for the same model and period; preserve raw records and route applicability.
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg accepted net part of one declared model
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_chassis_materials

Chassis mechanical completion electricity (chassis_electricity)

Meter chassis mechanical completion electricity and its attributable support demand separately. Include idle and fixture demand where present; do not duplicate another process meter.

• Selected flow: Electricity 890a70b7-b677-4e2a-8a1b-7d017e0a10ae
• Flow property / unit: Net calorific value 93a60a56-a3c8-11da-a746-0800200c9a66 / MJ; unit group 93a60a57-a3c8-11da-a746-0800200c9a66
• Amount rule: Collect the batch quantity in MJ and divide by accepted net output mass for the same model and period; preserve raw records and route applicability.
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg accepted net part of one declared model
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_chassis_energy

Outputs

Product flows

Accepted chassis output (chassis_product)

Chassis route only; weigh accepted net chassis and record count. This is the representative reference output, excluding packaging and complete-computer subassemblies.

• Selected flow: Steel computer chassis
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg; unit group 93a60a57-a4c8-11da-a746-0800200c9a66
• Amount rule: Collect the batch quantity in kg and divide by accepted net output mass for the same model and period; preserve raw records and route applicability.
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg accepted net part of one declared model
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_chassis_output

Waste flows

Rejected steel chassis (steel_reject)

Include discarded chassis from the mechanical route; exclude temporary rejects returned to the same batch. Record composition, mass and treatment destination.

• Selected flow: Steel scrap 9fe08808-a497-4b3c-8f8f-a8f6bbcae980
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg; unit group 93a60a57-a4c8-11da-a746-0800200c9a66
• Amount rule: Collect the batch quantity in kg and divide by accepted net output mass for the same model and period; preserve raw records and route applicability.
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg accepted net part of one declared model
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_chassis_waste

Process: Incomplete motherboard acceptance (board_acceptance)

Inputs

Product flows

Board awaiting acceptance testing (untested_board)

Board route only; supplier completes PCB fabrication and component assembly. Record configuration, mass and upstream burden.

• Selected flow: Populated computer motherboard without CPU and BIOS ROM, untested
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg; unit group 93a60a57-a4c8-11da-a746-0800200c9a66
• Amount rule: Collect the batch quantity in kg and divide by accepted net output mass for the same model and period; preserve raw records and route applicability.
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg accepted net part of one declared model
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_board_materials

Incomplete motherboard acceptance electricity (board_electricity)

Meter incomplete motherboard acceptance electricity and its attributable support demand separately. Include idle and fixture demand where present; do not duplicate another process meter.

• Selected flow: Electricity 890a70b7-b677-4e2a-8a1b-7d017e0a10ae
• Flow property / unit: Net calorific value 93a60a56-a3c8-11da-a746-0800200c9a66 / MJ; unit group 93a60a57-a3c8-11da-a746-0800200c9a66
• Amount rule: Collect the batch quantity in MJ and divide by accepted net output mass for the same model and period; preserve raw records and route applicability.
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg accepted net part of one declared model
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_board_energy

Outputs

Product flows

Accepted motherboard output (motherboard_product)

Board route only; record accepted board count and net mass. This replaces the representative reference product in a board-specific data package; never sum different part functions into one reference product.

• Selected flow: Computer motherboard without CPU and BIOS ROM, acceptance tested
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg; unit group 93a60a57-a4c8-11da-a746-0800200c9a66
• Amount rule: Collect the batch quantity in kg and divide by accepted net output mass for the same model and period; preserve raw records and route applicability.
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg accepted net part of one declared model
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_board_output

Waste flows

Rejected populated board (board_reject)

Include irreparable populated-board rejects; retain hazardous-component and waste-transfer records. Treatment burdens belong to the product system.

• Selected flow: Waste populated printed wiring board eb5ffe4a-49af-450c-9a31-3efdfd343f8a
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg; unit group 93a60a57-a4c8-11da-a746-0800200c9a66
• Amount rule: Collect the batch quantity in kg and divide by accepted net output mass for the same model and period; preserve raw records and route applicability.
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg accepted net part of one declared model
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_board_waste

Process: Packing (packing)

Inputs

Product flows

Shipping carton (box)

Include when corrugated boxes are supplied with the part; weigh cartons separately from net product.

• Selected flow: corrugated board boxes 4f197bec-7b3b-11dd-ad8b-0800200c9a66
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg; unit group 93a60a57-a4c8-11da-a746-0800200c9a66
• Amount rule: Collect the batch quantity in kg and divide by accepted net output mass for the same model and period; preserve raw records and route applicability.
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg accepted net part of one declared model
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_packing_materials

Protective polyethylene bag (bag)

Include only when this specific bag is used; record polymer grade, additives and mass. Electronic parts require declared electrostatic protection; ordinary LDPE is not presumed suitable.

• Selected flow: Low-density polyethylene protective bag
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg; unit group 93a60a57-a4c8-11da-a746-0800200c9a66
• Amount rule: Collect the batch quantity in kg and divide by accepted net output mass for the same model and period; preserve raw records and route applicability.
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg accepted net part of one declared model
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_packing_materials

Packing electricity (packing_electricity)

Meter packing electricity and its attributable support demand separately. Include idle and fixture demand where present; do not duplicate another process meter.

• Selected flow: Electricity 890a70b7-b677-4e2a-8a1b-7d017e0a10ae
• Flow property / unit: Net calorific value 93a60a56-a3c8-11da-a746-0800200c9a66 / MJ; unit group 93a60a57-a3c8-11da-a746-0800200c9a66
• Amount rule: Collect the batch quantity in MJ and divide by accepted net output mass for the same model and period; preserve raw records and route applicability.
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg accepted net part of one declared model
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_packing_energy

7. Allocation and Co-product Handling

rule_id	applies_to	rule	source_ids
separate_models	Shared finishing equipment	Separate routes and meter dedicated operations first. For inseparable shared demand, use a justified physical driver such as occupied test time; use economic allocation only if physical causation cannot be established and document sensitivity.	ghg-protocol-product-standard-2011
reject_burdens	Rework and scrap	Retain rework and rejected-part production burdens in accepted output. Record waste treatment and any recycling allocation transparently; never deduct a presumed virgin-material credit from scrap mass alone.	ghg-protocol-product-standard-2011

8. Foreground Data Collection, Calculation, and Quality Rules

Data Collection Protocols

protocol_id	process_id	flow_role	record_type	raw_fields	collection_method	unit	frequency	temporal_coverage	site_scope	aggregation_rule	quality_evidence
cp_chassis_materials	chassis_completion	Chassis shell and steel screws	Material ledger	model, lot, item identity, quantity issued, unused returns, stock change, mass per item, supplier, route	Weigh each material separately; reconcile issue records and BOM; retain upstream and shipment records	kg	Each lot	Declared representative production period covering normal and rework operation	Actual finalization site and named suppliers	Sum consumption by atomic flow and model; divide by accepted net model output	Calibrated scales, BOM revision, delivery notes, supplier coverage and receiving checks
cp_chassis_energy	chassis_completion	Electricity	Meter and test logs	meter start/end, kWh, test time, fixture load, idle load, model, lot, accepted output, allocation driver	Submeter or document an engineering allocation from measured loads and times	kWh then MJ	Each batch or logged test interval	Same period as material and output records	Chassis completion and its attributable support only	Convert kWh by 3.6; reconcile submeters to main meter before model allocation and normalization	Meter calibration, load records and unallocated-energy reconciliation
cp_chassis_output	chassis_completion	Accepted part	Production and quality ledger	model, configuration, counts started/accepted/reworked/rejected, net mass, test criteria and outcome	Weigh accepted units and reconcile lot disposition; document temporary test fixtures	kg and item count	Each lot	Same reporting period	Final acceptance gate	Accepted mass by model is the denominator; never pool chassis and board output	Drawing, signed test acceptance, scale evidence and traceable count reconciliation
cp_chassis_waste	chassis_completion	Each reject stream	Waste transfer ledger	stream identity, composition, hazardous components, mass, rework return, stock, destination, treatment route	Segregate and weigh each physical waste stream; reconcile transfers and storage change	kg	Each transfer with lot attribution	Same reporting period plus documented storage lag	Site and named waste receiver	Normalize net external discard by model accepted mass; attach treatment dataset without duplicating internal rework	Weigh tickets, receiver evidence and treatment-boundary check
cp_board_materials	board_acceptance	Populated incomplete motherboard	Material ledger	model, lot, item identity, quantity issued, unused returns, stock change, mass per item, supplier, route	Weigh each material separately; reconcile issue records and BOM; retain upstream and shipment records	kg	Each lot	Declared representative production period covering normal and rework operation	Actual finalization site and named suppliers	Sum consumption by atomic flow and model; divide by accepted net model output	Calibrated scales, BOM revision, delivery notes, supplier coverage and receiving checks
cp_board_energy	board_acceptance	Electricity	Meter and test logs	meter start/end, kWh, test time, fixture load, idle load, model, lot, accepted output, allocation driver	Submeter or document an engineering allocation from measured loads and times	kWh then MJ	Each batch or logged test interval	Same period as material and output records	Board acceptance testing and its attributable support only	Convert kWh by 3.6; reconcile submeters to main meter before model allocation and normalization	Meter calibration, load records and unallocated-energy reconciliation
cp_board_output	board_acceptance	Accepted part	Production and quality ledger	model, configuration, counts started/accepted/reworked/rejected, net mass, test criteria and outcome	Weigh accepted units and reconcile lot disposition; document temporary test fixtures	kg and item count	Each lot	Same reporting period	Final acceptance gate	Accepted mass by model is the denominator; never pool chassis and board output	Drawing, signed test acceptance, scale evidence and traceable count reconciliation
cp_board_waste	board_acceptance	Each reject stream	Waste transfer ledger	stream identity, composition, hazardous components, mass, rework return, stock, destination, treatment route	Segregate and weigh each physical waste stream; reconcile transfers and storage change	kg	Each transfer with lot attribution	Same reporting period plus documented storage lag	Site and named waste receiver	Normalize net external discard by model accepted mass; attach treatment dataset without duplicating internal rework	Weigh tickets, receiver evidence and treatment-boundary check
cp_packing_materials	packing	Each supplied packaging component	Material ledger	model, lot, item identity, quantity issued, unused returns, stock change, mass per item, supplier, route	Weigh each material separately; reconcile issue records and BOM; retain upstream and shipment records	kg	Each lot	Declared representative production period covering normal and rework operation	Actual finalization site and named suppliers	Sum consumption by atomic flow and model; divide by accepted net model output	Calibrated scales, BOM revision, delivery notes, supplier coverage and receiving checks
cp_packing_energy	packing	Electricity	Meter and test logs	meter start/end, kWh, test time, fixture load, idle load, model, lot, accepted output, allocation driver	Submeter or document an engineering allocation from measured loads and times	kWh then MJ	Each batch or logged test interval	Same period as material and output records	Packing and its attributable support only	Convert kWh by 3.6; reconcile submeters to main meter before model allocation and normalization	Meter calibration, load records and unallocated-energy reconciliation

Calculation Rules

rule_id	Applies to	Formula or rule	Inputs	Output	source_ids
batch_normalization	Each atomic exchange	q_i = Q_i / M_a; M_a is accepted net mass of the same model; reject zero or unknown denominators	Measured batch exchange Q_i and accepted mass M_a	Exchange per kg accepted part
count_conversion	Item-count receipts	M = N times measured mean item mass for the same model and lot; retain sampling and variability	Count N and measured item mass	kg
material_check	Part material	Issued material minus unused returns equals accepted retained material plus discarded material plus net work-in-progress change; investigate residuals against documented measurement uncertainty	Material ledger, output and waste records	Reconciliation residual

Data Quality Requirements

requirement_id	Applies to	Requirement	Evidence
identity_quality	All part models	Record function, CPU/BIOS state, material and interface revision; do not infer a complete-computer service from a part mass	BOM, drawing, acceptance record; cbp-n304809-2019, cbp-n025223-2008
coverage_quality	Supplier and site linkage	Confirm where fabrication stops and finalization starts, including freight; quantify any missing coverage before using the package as a cradle-to-gate input	Supplier dataset scope, site process map and shipment records
range_quality	Exchange amounts	Use measured foreground quantities. No universal empirical consumption or yield range is prescribed for these heterogeneous parts; retain uncertainty from meters, sampling and allocation	Raw ledgers and uncertainty calculations
route_quality	Applicability	Distinguish measured zero, evidenced absence and missing data. Additional real components, process chemicals and waste streams require separate atomic rows	Site walkthrough, BOM, purchase and waste records

9. Validation Rules

rule_id	applies_to	rule	source_ids
one_reference	Reference flow	Require one eligible part model, one reference output, 1 kg net basis and all qualifiers. Never sum chassis and motherboard outputs into an interchangeable product.
ledger_validation	Quantities	Require a positive accepted-output denominator; reconcile count, mass, rejects, rework and stock movement with documented uncertainty.
boundary_validation	Completeness	Verify every supplier/freight/treatment link and onsite exchange; reject a cradle-to-gate claim supported only by finalization electricity and purchased-part mass.
identity_validation	UUIDs	Adopt only exact public flow identities of the right state, type, property and unit. A blank UUID remains an explicit identity gap and never licenses a proxy or omitted exchange.
comparability	Downstream claims	Do not use mass-normalized parts for comparative assertions without matching function, interfaces, host use and lifetime.	ghg-protocol-product-standard-2011

10. Published Dataset Profile

Field	Value
dataset_role	Foreground production package; a reviewed complete package may become a secondary_dataset
downstream_use	background_dataset input to OEM computer assembly or replacement-part lifecycle models
allowed_use	Model-specific declared-boundary part supply; cradle-to-gate only when upstream, freight and treatment coverage are complete
excluded_use	Whole-computer footprint; universal part average; cross-function comparison; unqualified full life cycle claim
required_metadata	Model, route, configuration, item mass, period, site, supplier datasets, freight, tests, allocation, waste treatment and reference identity
required_quality_disclosure	Measured coverage, gaps, unit conversion, uncertainty, non-applicability evidence and upstream boundary reconciliation
update_trigger	BOM, material, supplier, test protocol, process location, yield, electricity supply or boundary changes

11. Data Sources

Source id	Type	Reference	Used for
un-cpc-3-0-structure-2025	official_guidance	United Nations, CPC Version 3.0 structure, 30 June 2025; https://unstats.un.org/unsd/classifications/Econ/Download/In%20Text/CPC_Ver_3.0_Structure_30Jun2025.csv ; retrieved 2026-09-09	Product category identity and adjacent-category separation; no amount ranges
cbp-n304809-2019	official_guidance	US CBP ruling N304809, 27 June 2019; https://rulings.cbp.gov/api/getdoc/ny/2019/N304809	Concrete steel computer chassis boundary and declared installed-component state; no current tariff rule adopted
cbp-n025223-2008	official_guidance	US CBP ruling N025223, 24 April 2008; https://rulings.cbp.gov/api/getdoc/ny/2008/N025223	Motherboard without CPU/BIOS versus processing-machine state; no trade-agreement or tariff rule adopted
ghg-protocol-product-standard-2011	standard	WRI/WBCSD, Product Life Cycle Accounting and Reporting Standard, 2011, sections 7.3.7 and 9.3; https://ghgprotocol.org/sites/default/files/ghgp/standards/Product-Life-Cycle-Accounting-Reporting-Standard_041613.pdf ; retrieved 2026-09-09	Intermediate-product boundary disclosure and allocation hierarchy, adapted to inventory collection; not a claim of multi-impact certification