Every compliance change has a cascade. See yours before validation fails.
The Impact Intelligence Verification Graph Engine (VGE) traverses your compliance graph to surface impacts across:
- SOPs, quality gates, and control point hierarchies
- Training records and competency matrices
- Supplier qualifications and audit evidence chains
- Validation protocols (IQ/OQ/PQ) and CAPA linkages
Preview mode lets you ask 'what if?' before committing to re-validation - with evidence requirements mapped to your configured compliance rules.
Compliance cascade map
Surface every impacted node across your compliance framework before approvals:
- SOPs, quality gates, and inspection steps
- Training records and supplier qualifications
- Validation protocols and audit evidence
Validation pack preview
Draft re-execution plans without committing changes:
- IQ/OQ/PQ re-execution scope and quality gate checklists
- Training matrices and CAPA verification tasks
- Evidence requirement checklists
Evidence gap analysis
Identify gaps with severity mapped to your risk and compliance frameworks:
- Risk scoring via ISO 14971, ICH Q9(R1), FMEA
- Compliance mapping to QMSR/ISO 13485 and 21 CFR Part 11
- Traceability gaps and incomplete training records
Console preview
Change intelligence report
Seed change
SOP revision: SOP-4417 Bioburden Hold → updated acceptance criteria
Change impact
61 of 290 nodes (21%)
across 5 domains
Severity hotspots
5
critical
NRE estimate
$135K – $210K
likely $165K
Schedule delta
+28d
critical path
Impact cascade / sample path
SOP defines acceptance criteria for QG-220 bioburden hold
via document_control
5 IQ/OQ protocols require re-validation
via validation
12 training records need refresher completion
via training
3 audit gates require evidence refresh
via audit
8 controlled documents need revision
via document_control
1 another SOP revision overlaps this compliance scope
- └─ SOP-4421 Environmental monitoring frequency change - clean rooms A/B 5 shared nodes pending QA review
Verification pack / draft
- 5 IQ/OQ re-validations
- 12 training record refreshers
- 3 audit gate evidence updates
- 8 controlled document revisions
Cost estimate: NRE $135K – $210K (likely $165K)
- ├─ Validation protocol rewrite: $34K – $52K (IQ/OQ/PQ amendments)
- ├─ Regulatory filing update: $18K – $28K (site master file revision)
- ├─ Training re-qualification: $8K – $12K (42 operators affected)
- ├─ Schedule penalty: +28d delays next batch release
The problem
You cannot defensibly prove impact assessment and traceability across silos.
Quality revises an inspection SOP. Your document controller says 'just a routine update.' Three weeks later, you discover it invalidated 12 training records, requires re-validation of 5 quality gates, impacts 3 supplier audits, and created CAPA evidence gaps that block an FDA submission.
Hidden cost of blind changes
- Invalidated training records discovered during pre-audit review, weeks after SOP release.
- Supplier re-qualification cascades triggered without validation protocols or resource plans.
- Quality gate threshold changes that break validation protocols for in-process lots.
- Audit evidence gaps created by document revisions nobody mapped to CAPA root causes.
Key capabilities
Active intelligence for regulated industries changes.
SOP cascade analysis
Walk SOP hierarchies to surface every impacted training record, quality gate, work instruction, validation protocol, and audit evidence link across your full quality framework.
Quality gate propagation
Trace quality gate threshold changes through validation protocols, inspection plans, training matrices, and supplier qualifications to reveal the full re-validation impact before release.
Training impact detection
Detect when an SOP, work instruction, or process change invalidates training records and generate competency assessment plans with evidence requirements mapped to 21 CFR 211.25 (drugs) / 820.25 (devices), with Part 11 controls when records are electronic.
Supplier qualification checks
Identify every supplier audit, qualification protocol, and material certification affected by a proposed change, with gap analysis for missing evidence.
Audit evidence generation
Assemble audit-ready evidence packs from existing records, highlight missing artifacts, and track sign-off status across impacted nodes, validation requirements, proof paths, and training records.
CAPA root cause traversal
Map which CAPA investigations, root cause analyses, and corrective actions are invalidated by a change, before effectiveness checks fail or audits discover the gap.
Validation protocol impact
Verify whether IQ/OQ/PQ protocols, process validation, cleaning validation, or method validation require re-execution based on change scope and effectivity dates.
Regulatory submission triggers
Detect when a change triggers regulatory submission requirements (new 510(k) determination, CE marking technical documentation per EU MDR Annex II/III, Health Canada licence amendment) based on device classification and change risk assessment.
How it works
From change signal to verified action.
Seed the change
A ChangeControl record identifies what's changing: SOP revision, quality gate threshold, supplier re-qualification, or validation protocol update.
Traverse the graph
Domain providers walk the dependency graph across SOPs, training records, quality gates, supplier qualifications, validation protocols, CAPA investigations, and audit evidence links.
Score severity
Severity is scored from risk and compliance factors - criticality, validated state, effectivity, open deviations/CAPA, data integrity exposure - and mapped to your risk method (ISO 14971, ICH Q9(R1), or FMEA) and compliance obligations (QMSR / ISO 13485, EU GMP Annex 11).
Detect collisions
Cross-change collision detection reveals when concurrent SOP revisions, quality gate updates, or CAPA remediations create overlapping blast radii that require quality review.
Generate verification packs
Assemble draft validation protocols, training assessment plans, supplier re-qualification checklists, CAPA verification tasks, and evidence requirement checklists from existing records - preview them before committing.
Map evidence gaps
Identify missing proof paths, incomplete training records, validation protocol gaps, and audit evidence deficiencies with traceability to regulatory requirements.
Act or iterate
Apply the change with idempotency keys to persist verification packs and evidence links, or adjust parameters and re-run the analysis in preview mode.
Hybrid graph model
VGE traverses your existing quality system schema with no data migration required. The engine analyzes dependencies across SOPs, training records, quality gates, validation protocols, and supplier qualifications.
Virtual edges
Inferred dependencies from SOP hierarchies, training matrices, validation protocol references, and CAPA investigation links.
Explicit edges
Tenant-defined dependencies with rationale and supporting context, e.g., linking a supplier qualification to specific quality gates or validation protocols.
Policy edges
Rules mapping compliance frameworks (ISO 9001, QMSR / ISO 13485, GMP, HACCP) and risk methods (ISO 14971, ICH Q9(R1)) to required validation work, training requirements, and audit evidence for each change type. Part 11 controls apply when records are electronic.
Regulated Industries impact scenarios
Real change scenarios in regulated industries.
Impact Intelligence adapts to your domain’s change patterns, compliance frameworks, and verification workflows. These are representative output examples from the VGE computation pipeline.
Regulated Industries
12 training records · 5 IQ/OQ protocols · Validation: +28 daysTrigger
SOP revision affecting quality-critical process
Impact
12 training records invalidated, 5 validation protocols require re-execution, 3 supplier audit checklists outdated, 2 CAPA effectiveness checks broken.
Verification Pack
Training competency assessment plan, IQ/OQ re-validation protocols, supplier audit update package, CAPA verification task list, audit evidence bundle.
Metrics
12 training records · 5 IQ/OQ protocols · Validation: +28 days
Regulated Industries
Schedule: +22 days · 6 product lines affected · 14 training recordsTrigger
Quality gate threshold change
Impact
6 product lines with active lots affected, 8 inspection plans outdated, 14 training records require competency re-assessment, 2 customer regulatory commitments impacted.
Verification Pack
Inspection plan updates, training re-assessment schedule, lot disposition review, customer notification package, validation protocol amendments.
Metrics
Schedule: +22 days · 6 product lines affected · 14 training records
Regulated Industries
17 training records · 4 validation protocols · CAPA closure: +35 daysTrigger
Audit finding requiring SOP remediation
Impact
CAPA root cause cascade across 9 SOPs, 17 training records invalidated, 4 validation protocols broken, 3 supplier qualifications require re-audit.
Verification Pack
CAPA verification plan, SOP revision package, training matrix update, validation protocol re-execution schedule, supplier re-audit checklist.
Metrics
17 training records · 4 validation protocols · CAPA closure: +35 days
Regulated Industries
5 validation protocols · 11 lot holds · Submission delay: +42 daysTrigger
Supplier re-qualification cascade
Impact
Alternate source impact across 7 material specifications, 11 quality gate holds on in-process lots, 5 validation protocols require amendment, 2 regulatory submissions affected.
Verification Pack
Alternate supplier qualification plan, quality gate hold/release checklist, validation protocol amendment package, regulatory submission update bundle.
Metrics
5 validation protocols · 11 lot holds · Submission delay: +42 days
Regulated Industries
34 nodes impacted · 3 regulatory submissions · Schedule: +90 daysTrigger
Validation protocol update triggering regulatory submission
Impact
Full change impact spanning 34 nodes across SOPs/quality gates/training, 3 regulatory submissions (new 510(k) determination, CE marking technical documentation per EU MDR), 8 supplier notifications required.
Verification Pack
New 510(k) change assessment package, SOP document package, training competency matrix, supplier change notification package, audit evidence index.
Metrics
34 nodes impacted · 3 regulatory submissions · Schedule: +90 days
Impact Intelligence for Regulated Industries
Operational scale that makes impact analysis possible.
VGE runs on tenant-owned data: schema depth, API breadth, and deterministic telemetry that keeps change reviews consistent.
Domain providers
15+
5 cross-industry baseline + 10 domain-specific providers (composition structures, compliance, verification, 3D/geometric, procurement, inventory, capital assets, execution chains), each self-describing with SemVer and cost tiers.
Sync analysis
≤2s
Typical graph traversal (≤1K nodes) with batch-first providers and per-request caching.
Async analysis
≤30s
Complex traversals (≤10K nodes) with optional Redis acceleration and per-provider timing.
Impact demo
Impact Intelligence for Regulated Industries
Preview change impact, severity scoring, and verification packs before approvals.
Change impact
61 nodes
Projected change
Severity hotspots
5
Projected change
NRE estimate
$165K
Projected change
Schedule delta
+28d
Projected change
Sample finding
Surface every impacted node across your compliance framework before approvals:
Impact cascade
Seed the change
Virtual edges
Explicit edges
Policy edges
API preview
Schema-stable endpoints for impact intelligence.
Impact Intelligence is designed as a tenant-owned API surface with preview-first semantics, deterministic run snapshots, and export-ready results.
Preview vs apply
Every request can run in preview mode to generate impact results without mutating data. Apply mode uses idempotency keys to persist verification packs safely.
View developer docsPOST Start impact analysis
Seed a new analysis for an SOP revision, quality gate change, CAPA remediation, or validation protocol update. Preview mode is the default.
POST /api/v1/change-controls/{id}/impact/runThe ChangeControl record (created separately) carries the change details: SOP-4417 Rev C → Rev D updating in-process inspection criteria for aseptic filling, cascading through quality gates QG-220 through QG-225, validation protocols VP-IQ-0087 and VP-OQ-0088, and batch records BR-2026-0041 through BR-2026-0063.
Request
{
"detect_collisions": true
}Response
{
"schema_version": "vge.graph_result.v1",
"run_id": 503,
"nodes": [
{
"node_ref": {
"resource_type": "quality_gate",
"resource_id": 220,
"display_name": "QG-220 - Aseptic Fill Bioburden Hold",
"display_code": "QG-220",
"status": "Re-validation Required",
"tags": [
"GMP",
"21 CFR Part 211",
"aseptic"
]
},
"severity": 0.94,
"depth": 1
},
{
"node_ref": {
"resource_type": "validation_protocol",
"resource_id": 87,
"display_name": "VP-IQ-0087 - Installation Qualification, Filling Line 3",
"display_code": "VP-IQ-0087",
"status": "Re-execution Required",
"tags": [
"IQ",
"21 CFR Part 211",
"filling"
]
},
"severity": 0.91,
"depth": 2
},
{
"node_ref": {
"resource_type": "training_record",
"resource_id": 3341,
"display_name": "TR-3341 - Aseptic Gowning Competency, SOP-4417 Rev C",
"display_code": "TR-3341",
"status": "Invalidated",
"tags": [
"competency",
"GMP",
"annual requalification"
]
},
"severity": 0.87,
"depth": 2
},
{
"node_ref": {
"resource_type": "capa_investigation",
"resource_id": 1192,
"display_name": "CAPA-1192 - Bioburden Excursion Root Cause",
"display_code": "CAPA-1192",
"status": "Effectiveness Check Broken",
"tags": [
"CAPA",
"deviation",
"FDA observation"
]
},
"severity": 0.82,
"depth": 3
}
],
"edges": [
{
"source": {
"resource_type": "sop",
"display_code": "SOP-4417-D"
},
"target": {
"resource_type": "quality_gate",
"display_code": "QG-220"
},
"edge_type": "GOVERNS",
"provider": "document_control",
"label": "SOP-4417 defines acceptance criteria for QG-220 bioburden hold"
},
{
"source": {
"resource_type": "quality_gate",
"display_code": "QG-220"
},
"target": {
"resource_type": "validation_protocol",
"display_code": "VP-IQ-0087"
},
"edge_type": "VALIDATED_BY",
"provider": "validation",
"label": "QG-220 acceptance criteria validated under IQ protocol VP-IQ-0087"
},
{
"source": {
"resource_type": "sop",
"display_code": "SOP-4417-D"
},
"target": {
"resource_type": "training_record",
"display_code": "TR-3341"
},
"edge_type": "REQUIRES_TRAINING",
"provider": "training_matrix",
"label": "SOP-4417 Rev C training - 12 operators require requalification on Rev D"
}
],
"stats": {
"node_count": 61,
"edge_count": 104,
"provider_counts": {
"document_control": 18,
"validation": 14,
"training_matrix": 12,
"quality_gate": 9,
"capa": 5,
"batch_record": 3
},
"truncated": false,
"collisions": {
"collision_count": 0,
"collision_severity": "NONE"
}
}
}GET Retrieve compliance cascade
Get the full impact graph with severity scores, compliance framework mapping, and affected validation protocols.
GET /api/v1/change-controls/{id}/impactGET Trace proof path
Explain why a specific training record, quality gate, or validation protocol is impacted, auditable at every SOP hop.
GET /api/v1/change-controls/{id}/impact/explain?node_key=validation_protocol:87:headResponse
{
"run_id": 503,
"target_node_key": "validation_protocol:87:head",
"path_node_keys": [
"sop:4417:head",
"quality_gate:220:head",
"validation_protocol:87:head"
],
"path_edges": [
{
"edge_type": "GOVERNS",
"provider": "document_control",
"label": "SOP-4417 Rev D revises bioburden acceptance criteria referenced by QG-220"
},
{
"edge_type": "VALIDATED_BY",
"provider": "validation",
"label": "QG-220 acceptance criteria validated under VP-IQ-0087 - IQ protocol requires re-execution because qualified parameters changed"
}
],
"notes": "2-hop path: SOP revision → quality gate → IQ validation protocol. VP-IQ-0087 must be re-executed because SOP-4417 Rev D changes the bioburden hold limits that QG-220 enforces, and VP-IQ-0087 qualified those limits during original installation qualification."
}GET Detect cross-change collisions
Find where concurrent SOP revisions or CAPA remediations create overlapping blast radii on shared validation protocols.
GET /api/v1/change-controls/{id}/impact/collisionsResponse
{
"collision_count": 2,
"colliding_change_ids": [
498,
511
],
"collision_severity": "HIGH",
"top_overlapping_nodes": [
{
"node_key": "validation_protocol:87:head",
"severity": 0.91,
"change_ids": [
503,
498
],
"display": "VP-IQ-0087 - overlaps with CC-498 (cleaning validation protocol update for Filling Line 3)"
},
{
"node_key": "training_record:3341:head",
"severity": 0.87,
"change_ids": [
503,
511
],
"display": "TR-3341 Aseptic Gowning Competency - overlaps with CC-511 (CAPA-1204 gowning procedure remediation)"
}
]
}POST Generate verification pack
Generate validation protocols, training assessment plans, and CAPA verification tasks in preview or apply mode.
POST /api/v1/change-controls/{id}/verification-pack/generateRequest
{
"mode": "preview"
}Response
{
"proposed_validations": [
{
"validation_type": "inspection",
"validation_meta": {
"description": "IQ/OQ re-execution for Filling Line 3 - SOP-4417 Rev D changes bioburden hold limits validated under VP-IQ-0087 and VP-OQ-0088",
"affected_nodes": [
"validation_protocol:87:head",
"validation_protocol:88:head"
],
"regulatory_basis": "21 CFR Part 211.68 (equipment qualification)",
"protocols": [
"VP-IQ-0087 (Installation Qualification)",
"VP-OQ-0088 (Operational Qualification)"
]
}
},
{
"validation_type": "checklist",
"validation_meta": {
"description": "Competency re-assessment for 12 aseptic filling operators - SOP-4417 Rev D invalidates gowning and bioburden monitoring training records TR-3341 through TR-3352",
"affected_nodes": [
"training_record:3341:head",
"training_record:3342:head",
"training_record:3352:head"
],
"regulatory_basis": "21 CFR Part 211.25, GMP Annex 1"
}
},
{
"validation_type": "inspection",
"validation_meta": {
"description": "CAPA-1192 effectiveness check invalidated - bioburden excursion root cause references SOP-4417 Rev C acceptance criteria now superseded by Rev D",
"affected_nodes": [
"capa_investigation:1192:head"
],
"regulatory_basis": "21 CFR Part 820.100 (CAPA)",
"deviation_ref": "DEV-2025-0847"
}
},
{
"validation_type": "checklist",
"validation_meta": {
"description": "Quality gate re-certification - update acceptance criteria for QG-220 through QG-225 to reflect SOP-4417 Rev D bioburden limits, batch record template updates for BR-2026 series",
"affected_nodes": [
"quality_gate:220:head",
"quality_gate:221:head",
"quality_gate:225:head"
]
}
}
],
"proposed_external_acknowledgements": [
{
"target_type": "AUDITOR",
"target_id": 2810,
"reason": "FDA inspection observation AF-2025-031 references SOP-4417 Rev C - updated evidence package required for observation close-out"
}
]
}POST Compute cost estimate
Estimate NRE costs (asset reconfiguration, documentation updates, replanning) and recurring impact (per-unit validation cost changes, added verification steps) with min/likely/max uncertainty bounds.
POST /api/v1/change-controls/{id}/cost-estimateResponse
{
"estimate_id": 1089,
"impact_analysis_run_id": 503,
"line_items": [
{
"cost_driver_type": "nre",
"description": "IQ/OQ re-execution for Filling Line 3 - VP-IQ-0087 and VP-OQ-0088, 3 consecutive media fill runs per protocol",
"quantity": 6,
"unit_rate": 12500,
"cost_phase": "nre",
"min_cost": 62000,
"likely_cost": 75000,
"max_cost": 95000,
"confidence": 0.85
},
{
"cost_driver_type": "nre",
"description": "Aseptic gowning and bioburden monitoring requalification - 12 operators, competency assessment per 21 CFR Part 211.25",
"quantity": 12,
"unit_rate": 2800,
"cost_phase": "nre",
"min_cost": 28000,
"likely_cost": 33600,
"max_cost": 42000,
"confidence": 0.88
},
{
"cost_driver_type": "nre",
"description": "SOP revision package - SOP-4417 Rev D, 6 quality gate criteria updates (QG-220–QG-225), batch record template revisions, 21 CFR Part 11 compliant e-signatures",
"quantity": 9,
"unit_rate": 3200,
"cost_phase": "nre",
"min_cost": 24000,
"likely_cost": 28800,
"max_cost": 36000,
"confidence": 0.9
},
{
"cost_driver_type": "nre",
"description": "CAPA-1192 effectiveness re-verification - root cause analysis update, deviation report DEV-2025-0847 amendment, inspection observation AF-2025-031 evidence refresh",
"quantity": 1,
"unit_rate": 18500,
"cost_phase": "nre",
"min_cost": 14000,
"likely_cost": 18500,
"max_cost": 24000,
"confidence": 0.72
},
{
"cost_driver_type": "nre",
"description": "Audit evidence package rebuild - FDA observation response update, traceability matrix revision, 21 CFR Part 11 electronic record remediation",
"quantity": 1,
"unit_rate": 9100,
"cost_phase": "nre",
"min_cost": 7000,
"likely_cost": 9100,
"max_cost": 12500,
"confidence": 0.78
},
{
"cost_driver_type": "recurring",
"description": "Per-batch added verification step - bioburden re-testing for in-process lots under revised SOP-4417 Rev D criteria",
"quantity": 1,
"unit_rate": 145,
"cost_phase": "recurring",
"min_cost": 110,
"likely_cost": 145,
"max_cost": 195,
"confidence": 0.92,
"justification": "Additional bioburden sample pull and rapid micro assay per batch under revised hold-time limits"
}
],
"nre_range": {
"min": 135000,
"likely": 165000,
"max": 209500
},
"recurring_range": {
"min": 110,
"likely": 145,
"max": 195,
"currency": "USD",
"description": "Per-batch recurring cost increase from added bioburden verification step under SOP-4417 Rev D"
},
"schedule_impact": {
"min_schedule_days": 21,
"likely_schedule_days": 28,
"max_schedule_days": 38,
"critical_path_nodes": [
"validation_protocol:87:head",
"validation_protocol:88:head"
]
},
"confidence": 0.84,
"confidence_notes": "Estimate calibrated from your operational data. IQ/OQ re-execution timeline for Filling Line 3 is the primary uncertainty driver - media fill scheduling depends on production window availability.",
"justification_summary": "SOP-4417 Rev C → Rev D drives $165K NRE (IQ/OQ re-execution across 2 validation protocols with 3 media fills each, 12-operator requalification program, 9 document updates with 21 CFR Part 11 e-signatures, CAPA-1192 re-verification, and audit evidence rebuild) plus $145/batch recurring bioburden verification cost. Validation protocol re-execution is the critical path at 28 days."
}GET Export compliance graph
Export the full compliance graph as JSON, CSV, audit-ready PDF bundle, or GraphML for integration with QMS platforms or regulatory portals.
GET /api/v1/impact-analysis-runs/{run_id}/export?format=graphmlPreview endpoints reflect the planned VGE surface. Final routes may adjust as the engine deploys to production.
FAQ
Common questions about Impact Intelligence for regulated industries.
How does VGE handle multi-tiered SOP hierarchies?
VGE traverses the full SOP structure. Depth and effectivity rules are configurable per compliance framework.
Can Impact Intelligence preview compliance cascades before SOP release?
Yes. Preview mode is the default. Seed an analysis with your proposed SOP revision or quality gate change and VGE computes the full compliance cascade, validation work, and evidence gaps without persisting any changes. Iterate as many times as needed before applying.
What happens when a training record expires mid-production?
VGE detects the expiration as a change signal and computes the downstream impact: affected quality gates, validation protocols requiring competency re-assessment, in-process lots requiring hold, and alternate qualified personnel. The resulting verification pack highlights retraining tasks with evidence requirements and regulatory rationale.
Does it integrate with our existing QMS or EQMS system?
Impact Intelligence runs on your EquatorOps quality data. Results export as JSON, CSV, audit-ready PDF bundles, or GraphML for integration with QMS platforms (MasterControl, TrackWise, Veeva Vault), ERP quality modules, and regulatory submission portals.
How are concurrent SOP revisions and CAPA remediations detected?
Cross-change collision detection compares blast radii of all active and in-review changes. When overlapping nodes are found (e.g., same training record or validation protocol), high-severity collisions automatically create quality review queue entries with evidence paths for human resolution.
Are evidence gap analyses audit-ready?
Evidence gap analyses map directly to compliance frameworks (QMSR / ISO 13485, GMP, HACCP) with Part 11 controls for electronic records. Gaps include severity scores, proof path explanations, remediation steps, and regulatory requirement citations - formatted for FDA inspection responses, ISO audit reports, or Health Canada submissions.
Can we customize severity scoring for our risk method?
Yes. Severity parameters are tenant-configurable to match your risk profile. Map them to your risk method (ISO 14971 for devices, ICH Q9(R1) for pharma, or FMEA) so scoring reflects your actual risk tolerance.
What about changes that affect supplier qualifications?
Supplier providers traverse qualification-to-quality-gate relationships, audit schedules, material certifications, and re-qualification protocols. A supplier change surfaces every quality gate, validation protocol, and in-process lot that depends on that supplier's qualification status.
Does Impact Intelligence support QMSR (21 CFR Part 820 as amended)?
Yes. For medical device quality systems, policy edges reference QMSR aligned to ISO 13485:2016. When a change triggers QMS document updates, Impact Intelligence maps affected procedures, work instructions, and records against QMSR requirements and flags notified body review effort where applicable.
How does 21 CFR Part 11 apply within Impact Intelligence?
Part 11 controls apply to electronic records and electronic signatures throughout the change control workflow - audit trail integrity, e-signature authentication, and record retention. Part 11 is not used as the basis for validation re-execution or training requirements; those map to the applicable product-specific regulations (211.25 for drugs, 820.25 for devices) and your configured risk method.