Jet Mill (Micronizer) Requalification / Periodic Review Strategy

Jet Mill (Micronizer) Requalification: Scope, Expectations, and Risk Management

The jet mill, also commonly referred to as a micronizer, is a precision-impact milling device used in the manufacture of oral solid dosage (OSD) forms, such as tablets and capsules. In this context, its principle function is micronization—the reduction of active pharmaceutical ingredient (API) or excipient particle size to a defined, reproducible fine range, often sub-10 microns. Particle size control in granulation and blending directly impacts content uniformity, dissolution, bioavailability, and mechanical characteristics of the final drug product. The jet mill is thus a core processing asset within OSD lines, typically stationed downstream of coarse milling and upstream of blending operations, with its use strictly bounded by the product-specific process definition justified during development.

Position and Boundaries in OSD Manufacturing

In the typical OSD manufacturing workflow, the jet mill is used to impart desired particle size distributions—most often to APIs that are poorly soluble or require specific physicochemical performance. The equipment is not generally employed for excipient-only batches, nor for any function beyond micronization by high-velocity particle collision (as opposed to mechanical attrition). Its use is tightly regulated within batch records and is permitted only for pre-qualified product/matrix combinations, as validated through process development. Requalification maintains this state of compliance, demonstrating ongoing control over all critical processing attributes.

Validation and Requalification Scope

Jet mill requalification, also referred to as periodic review or continued verification, is bounded by the following scope principles:

• In-Scope:
  • Mechanical and operational qualification (OQ/PQ) for micronization of registered product APIs used in OSD forms
  • Verification of critical parameters: airflow rate, feed rate, grinding pressure, particle size output
  • Assessment of product contact materials’ integrity and cleanability
  • Evaluation of integrated controls and safety features, including interlocks and environmental monitoring points
  • Assessment of data integrity for electronic batch records and process control data
  • Inspection and testing of HEPA filtration, exhaust segregation, and dust containment features
• Out-of-Scope:
  • Qualification of utilities supplying non-product-contact media (general compressed air supply upstream of final air preparation units)
  • Validation of cleaning agents (unless part of cleaning validation program)
  • IT infrastructure qualification outside equipment-specific data storage/control boundaries
  • Non-GMP usage such as R&D trials not feeding into commercial lots
  • Maintenance of non-critical ancillary systems (e.g., building-wide dust collection systems)

Criticality Assessment

As a processing device directly impacting material quality, the jet mill stands as critical to product safety and efficacy. To define a proportionate validation and requalification strategy, a thorough and structured criticality assessment is essential:

• Product Quality Impact: Inadequate or variable particle size distribution can affect dissolution rate, blend/mix homogeneity, and tablet compaction.
• Patient Risk: Poorly controlled micronization may result in sub- or supra-therapeutic dosing, especially for high-potency APIs.
• Data Integrity Impact: Electronic batch records and trending of process data must be secure, accurate, and attributable.
• Contamination Risk: Residue carryover (product-to-product or batch-to-batch) can potentially result in cross-contamination; containment failures may yield dust exposure.
• Environment, Health, Safety (EHS) Risk: Uncontained fine particulates pose inhalation hazards for operators; dust explosion potential if not properly controlled.

GMP Expectations for Jet Mill Qualification and Requalification

GMP compliance for jet mills demands demonstration of state-of-control across each lifecycle stage, including design, installation, operation, and performance, with emphasis on:

• Design Qualification (DQ): Ensuring specifications and intended use are reflected in equipment and process controls.
• Installation Qualification (IQ): Verification that the mill is installed according to manufacturer’s specifications and facility requirements.
• Operational Qualification (OQ): Confirmation that controls, safety systems, and operating ranges (e.g., airflow, pressure) perform as intended.
• Performance Qualification (PQ): Demonstration under routine production conditions that the mill consistently produces material meeting particle size and other critical quality attributes (CQAs).
• Requalification/Periodic Review: Scheduled assessments (typically annual or biannual) and upon significant change or maintenance, evidencing sustained state-of-control.
• Change Control: Requalification triggers must be documented when significant hardware, software, or process changes occur.
• Documentation/Data Integrity: All test results, calibrations, and deviations must be safely archived, retrievable, and attributable per ALCOA+ principles.

User Requirement Specification (URS) Development for Jet Mill

The URS is the foundation for all qualification and requalification activities. For jet mills, a well-structured URS should clearly define:

• Functional Requirements: E.g., micronization capacity (kg/h), target d90 particle size, range of feedstock densities
• Performance Requirements: Operational pressures, safety interlocks, setpoints for alarms/alerts, environmental emission limits (dust, noise)
• Compliance Expectations: FDA/EU GMP compatibility, 21 CFR Part 11 readiness for electronic records, validation support
• Integration Requirements: Interfaces with upstream/downstream processing systems, automation platforms, or batch record systems
• Cleaning and Maintenance: Accessibility of product contact parts, materials of construction, maximum allowable residue limits
• Data Management: Secure storage and transmission of critical process data (pressures, times, particle size results)

Example URS Excerpt for a Jet Mill:

• Micronization capacity: 4–12 kg/h for API powders, d90 ≤10 µm
• Maximum operating pressure: 8 bar(g)
• Equipment to include GMP-compliant CIP (Clean-in-Place) system
• All product contact surfaces to be 316L stainless steel, Ra ≤ 0.6 µm
• HEPA filtration downstream to be validated to retain ≥99.97% particles ≥0.3 µm
• Interlocks to prevent operation unless all safety shields are in place
• 21 CFR Part 11-compliant electronic data capture and audit trail

Risk Assessment: FMEA-based Approach to Qualification Strategy

Applying FMEA (Failure Mode and Effects Analysis) principles in jet mill qualification allows for focus on critical steps and controls. Typical risk considerations include:

• Failure to Control Particle Size: Could result in OOS (out-of-specification) material; risk mitigated by validated in-line or at-line particle size measurement and periodic calibration.
• Uncontrolled Airflow or Pressure: May produce process variability; high-risk failure mode mitigated through sensor calibration, alert/alarm functions, and maintenance programs.
• Cross-Contamination via Inadequate Cleaning: Patient safety impact, managed through cleaning validation and regular swab testing of product contact parts.
• Data Loss or Manipulation: High data integrity risk, requiring robust electronic records, regular audit trail reviews, and user-access controls.
• Uncaptured Emissions/Operator Exposure: EHS and product purity risk, controlled through validated HEPA containment and operator training.

Below is a sample mapping of critical requirements to associated risks and controls/testing approaches, supporting both initial and periodic qualification strategies:

Through periodic requalification that focuses on these risk-based priorities, manufacturers can ensure the jet mill remains fit-for-purpose, GMP-compliant, and capable of producing OSD lots with the intended product quality attributes and patient safety profile.

The next sections continue the qualification storyline with practical tests, evidence expectations, and lifecycle controls appropriate for this equipment.

Jet Mill Requalification: Supplier Controls and Qualification Strategy

Effective jet mill requalification in GMP oral solid dosage (OSD) manufacturing environments depends on robust supplier controls and disciplined qualification activities. Ensuring that the micronizer continues to meet both regulatory and operational expectations for product quality, reliability, and safety requires periodic, risk-based review and confirmation of all critical elements from original design through ongoing operation. This section dissects in detail the necessary supplier qualifications, FAT/SAT strategies, and the rigor required in design and installation qualification phases for jet mills.

Supplier Controls: Rigorous Vendor Qualification and Documentation

The first foundation of sustainable jet mill requalification is the proactive qualification and continuous oversight of equipment suppliers. GMP mandates, as well as various regulatory guidelines (e.g., EU Annex 15, FDA Process Validation guidance), emphasize the lifecycle management of qualified vendors. For a jet mill, supplier controls must cover the following aspects:

• Supplier Qualification: Assess the vendor’s GMP compliance, engineering practices, calibration procedures, and history of equipment performance. This may involve onsite audits, reviewing previous project outcomes, and evaluating their change management processes.
• Document Package: A comprehensive documentation set is mandatory. This should include:
  • Design drawings (including P&IDs, General Arrangement, and Isometrics)
  • Bill of materials with material certificates (traceability, FDA/USP compliant where required)
  • Weld maps, surface finish certificates (if product-contact surfaces demand it)
  • Software documentation: If the jet mill includes PLC/HMI or data acquisition, software versioning, user manuals, validation/verification documents, and change logs are critical.
  • Operational and maintenance manuals
  • Calibration certificates for installed instruments (pressure, temperature, flow meters, load cells)
  • Certificates of compliance for elastomers, gaskets, O-rings, and other consumables in contact with product
• Material Certificates: All critical wetted and product-contact materials must be traced to source with positive material identification (PMI) and compliance with appropriate pharmacopeial standards (e.g., 316L stainless steel to EN 10204 3.1).
• Supplier Change Control: Vendors must demonstrate a systematic approach for notification and control of design, material, or software changes that could impact form, fit, or function of the jet mill.

Supplier Documentation & DQ/IQ Checklist

FAT/SAT Strategy for Jet Mill Requalification

Factory Acceptance Testing (FAT) and Site Acceptance Testing (SAT) are core milestones in ensuring the jet mill continues to meet both user and regulatory expectations throughout its lifecycle. For requalification, the approach integrates risk, accumulated deviation history, and any performance trends observed since initial qualification.

• FAT Activities:
  • What to test: Mechanical integrity, safety interlocks, control functionality, instrumentation calibration, and (where feasible) simulation of product processing cycles. Documentation review for completeness.
  • Who witnesses: User QA, Validation SME, process engineering, and supplier QA/engineering teams. Involvement is crucial for unbiased verification.
  • Recording deviations: All non-conformances are logged in FAT punch lists, with agreed remediation and risk assessments documented.
• SAT Activities:
  • What to test: Re-verification of installation, power, utility connections; redundant checks of critical startup sequences; end-to-end connectivity of automation and alarms; and integration with site environmental controls. Any transport or installation-induced changes are flagged.
  • Who witnesses: Plant QA/Validation, engineering, operator representatives, and, if requalification is supplier-supported, the vendor technical team.
  • Deviation management: All discrepancies versus URS/design/specs are recorded, with immediate triage and escalation to site change or deviation management as per SOP.

Design Qualification: Ensuring Fit-for-Purpose and Compliance

Design Qualification (DQ) for jet mill requalification must confirm that the system’s original design remains fit for its intended use and that any changes (materials, software, components) since the last qualification have been fully assessed. DQ includes:

• Design Reviews: Cross-functional panels (QA, process engineering, validation SME) review the design against the latest URS, focusing on containment (dust/leak prevention), cleanability (CIP/WIP if present), and operational safety.
• Drawings and Document Verification: Ensure that drawings match as-installed equipment; revised components are tracked and approved; interfaces to upstream and downstream equipment are current.
• Material and Component Confirmation: Reverification of materials of construction, especially for product-contact zones, to align with regulatory and product compatibility requirements.
• Hygienic Design: Confirm minimized crevices, proper weld quality, surface roughness, and avoidance of dead legs in product-contact areas; confirm capability for effective cleaning and inspection.

Installation Qualification (IQ): Planning and Execution

IQ for jet mill periodic requalification must verify that installation conditions and records remain compliant, and all critical utilities and devices are correctly integrated. IQ involves:

• Physical verification of anchor points, grouting (if required), orientation, and mounting as per approved drawings
• Utility connectivity and identification: dedicated electrical feeds, compressed air (dry, oil-free, particle free), process vacuum, and, if required, nitrogen or inerting lines
• Assessment and tagging of instrumentation (pressure sensors, flow meters) with up-to-date calibration certificates
• Labeling and legibility checks for all service valves, switches, electrical panels, and product lines
• Safety systems: e-stops, earth bonding, explosion venting (if relevant), and interlocks must be tested and their operation demonstrated
• Preparation of the as-built dossier: collated drawings, deviations, test records, and as-built markups for site archives
• Review and validation of cleaning validation status (impact on product quality and cross-contamination)

Environmental and Utility Dependencies: Critical Considerations

Jet mills have specific and often stringent environmental and utility requirements. For requalification, these dependencies must be reviewed and confirmed to still meet acceptance criteria:

• HVAC Environment/Class: Typically required in classified areas (ISO 7/8 or EU Grade D/C, depending on API and containment level). Temperature and humidity must be consistent with original validation.
• Compressed Air: Supply for jet milling must be dry (< -20°C dew point), oil-free (<0.01 mg/m³), particle-free (as per ISO 8573-1 Class 1 or better). Any compressed air used in direct product contact must be validated.
• Process Water (RO/PUW): If used for cleaning or product processing, conduct regular water quality checks in alignment with the applicable pharmacopeia.
• Steam (if used for CIP/SIP): Boiler chemical compatibility, steam quality (culinary grade, endotoxin limits), and condensate management should reflect original commissioning standards.
• Power Supply Quality: Reliance on stable 3-phase supply, phase sequence, and earthing integrity (voltage, frequency, and THD compliant with equipment specifications). Document power quality verification.

Failure to maintain these environmental and utility conditions risks non-compliance and potential compromise in jet mill performance and product quality—with traceability back to the documented risk and acceptance criteria.

Traceability Table Example: Jet Mill URS to Test Matrix

The next sections continue the qualification storyline with practical tests, evidence expectations, and lifecycle controls appropriate for this equipment.

Operational Qualification (OQ) Strategy for Jet Mill (Micronizer) Requalification

Operational Qualification (OQ) is a critical phase in the jet mill requalification process, focusing on verifying that the equipment consistently operates within defined parameters and meets its intended process requirements. For oral solid dosage production, the jet mill—also known as a micronizer—must be reassessed periodically through OQ to ensure it maintains high performance, safety, and compliance standards set by GMP and regulatory expectations. This segment presents a comprehensive approach to requalification, emphasizing the practical aspects relevant to OQ, instrumentation, data integrity, and GMP controls.

Core OQ Functional Tests for Jet Mill Requalification

The OQ protocol for a jet mill during requalification encompasses the following key functional verifications:

• Operating Range Verification: Test the jet mill’s ability to operate within defined pressure, airflow, and feed rate parameters. For instance, the mill should sustain a feed pressure range of 5.0–7.5 bar and maintain feed rates within 0.1–2.0 kg/min (example values).
• Alarm and Interlock Testing: Intentionally trigger process deviations to ensure all critical alarms (overpressure, filter differential pressure, air failure) activate promptly and relevant interlocks (preventing lid opening during operation) function reliably.
• Setpoint Verification: Confirm that the jet mill achieves and maintains user-defined setpoints, such as nozzle pressures, chamber temperatures, and classifier speeds, within specified tolerances (e.g., ±0.2 bar for nozzle pressure).
• Challenge Tests: Perform ‘worst case’ and routine challenge tests. Examples include overloading the feed hopper or briefly interrupting compressed air flow, observing that the system enters a safe, pre-programmed shutdown and recovers without drift or damage.

Instrumentation Checks and Calibration Verification

All critical instrumentation integrated with the jet mill must be confirmed as calibrated and functional prior to and during the OQ phase. The essential checks include:

• Pressure Gauges – Should display readings within ±1% of calibrated standard across the operational range (e.g., 0–10 bar).
• Temperature Sensors (if present) – Verify readings across the typical product contact range (e.g., 15°C–50°C) with traceable calibration certificates.
• Flow Meters – Check air and product feed flow meters for accuracy within validated range (e.g., ±2% of setpoint).
• Data Logging Devices – Review integration and calibration of any automatic recording instrumentation. Simulate input signals to confirm accurate data capture and time stamping.

Computerized and Automated Systems: Data Integrity Controls

For jet mills equipped with Programmable Logic Controllers (PLCs), Human-Machine Interfaces (HMIs), or integrated SCADA/MES, data integrity controls must be thoroughly verified:

• User Role Verification: Confirm role-based access controls are enforced. Operators should have limited rights (e.g., operate/run only), while supervisors and QA personnel possess configuration and review privileges.
• Audit Trail Activation: Ensure the system records all critical changes (parameter setpoints, alarm acknowledgment, access events), capturing user ID, time, and nature of change.
• Time Synchronization: Validate that system clocks are synchronized with plant time servers; timestamps across devices and logs must be within ±2 minutes.
• Backup and Restore Functionality: Execute a controlled backup and restoration of configuration and batch data. Confirm restoration integrity by comparing pre- and post-restore data sets.

GMP Controls: Integration and Compliance in Jet Mill Operation

Effective GMP controls are indispensable to jet mill requalification, assuring process integrity and product quality:

• Line Clearance: Before and after OQ activities, perform line clearance to ensure the absence of residual materials and cross-contamination risk. Use designated clearance checklists.
• Status Labeling: Attach clear and compliant status labels, indicating whether the equipment is “Under Qualification,” “Qualified,” or “Out of Service,” as appropriate throughout OQ.
• Logbooks and Electronic Records: Maintain comprehensive and contemporaneous entries for test runs, deviations, instrumentation checks, and calibration references during OQ. Where electronic records are used, verify compliance with 21 CFR Part 11 or relevant regional data integrity standards.
• Batch Record Integration: Simulate material processing as per a typical batch record. Validate that all OQ data flow securely and traceably into the manufacturing documentation.

Safety and Compliance Features Verification

Safety systems must be reevaluated with equal emphasis during OQ. This includes:

• Environmental, Health, and Safety (EHS) Features: Test local exhaust ventilation, dust containment barriers, and pressure relief valves. Verify that relief valves function at designated setpoints (e.g., valve lifts at 7.8 ±0.2 bar; example value).
• Mechanical and Electrical Guarding: Inspect and functionally test all physical guards and covers for interlock integrity—e.g., machine disables operation when panels are open.
• Emergency Stops and Fail-Safes: Test all emergency stop buttons and pull cords. The jet mill should halt immediately and safely upon activation from any location.

OQ Execution and Data Integrity Checklist for Jet Mill Requalification

The following checklist exemplifies the key actions and acceptance criteria commonly adopted during the OQ phase for jet mill requalification. Values shown are illustrative; actual acceptance criteria should be set based on jet mill brand, site policies, and historical data.

Comprehensive documentation of each completed test step, actual results, and any deviations encountered is essential. All results and raw data should be reviewed and approved by responsible QA personnel to fulfill regulatory and CGMP requirements associated with jet mill requalification.

The next sections continue the qualification storyline with practical tests, evidence expectations, and lifecycle controls appropriate for this equipment.

Performance Qualification (PQ) of Jet Mills: Strategy and Execution

Performance Qualification (PQ) for jet mills—critical for micronizing oral solid dosage materials—verifies consistent, robust performance under routine and worst-case operational scenarios. PQ not only ensures compliance but also cements confidence in ongoing product quality and patient safety, especially when requalification is required due to significant changes, deviations, or at predetermined review intervals.

PQ of a jet mill in a GMP environment focuses on verifying that the equipment consistently meets critical process parameters and predefined acceptance criteria for particle size distribution, output yield, and product quality. Both routine (nominal batch sizes, standard materials) and worst-case batches (largest or smallest batch size, hardest or most cohesive material, extended run time, maximum allowable input parameters) must be considered in the validation plan.

PQ Sampling Plan and Critical Test Parameters

Consideration must be given to both the physical performance and quality attributes of the processed material. The following table summarizes a typical PQ test plan for jet mill requalification:

The PQ protocol should include both in-process sampling and finished product testing. Special emphasis is placed on repeatability (same operator, same conditions, repeated runs) and reproducibility (different operators, equipment, or process times).

PQ Linkage to Cleaning Validation and Cross-Contamination Controls

Since the jet mill is direct product-contact equipment, a robust cleaning validation or cleaning verification program is integral to PQ. Effective cleaning is essential to prevent cross-contamination between different products and batch runs. During PQ, cleaning procedures are validated or verified by running worst-case products and following up with both visual inspections and analytical swabs/rinses on product-contact surfaces. Acceptance criteria for cleaning should be based on risk assessments, toxicity, solubility, and cleaning agent effectiveness and must be clearly documented.

PQ protocol and report must link performance results to the effectiveness of the cleaning procedure, highlighting any trends in cleaning failures, residue buildup, or process hold times between cleaning and reuse.

Continued Process Verification and Ongoing Qualification

Requalification of jet mills is not a one-time exercise, but part of a lifecycle validation approach. Continued process verification (CPV) is achieved by implementing a data-driven monitoring program that regularly evaluates critical parameters—particle size, yield, throughput, and cleaning effectiveness—using statistical process control charts or trending tools.

Routine checks include:

• Scheduled sample analysis from ongoing commercial batches
• Periodic review of cleaning verification/validation data
• Annual product quality and batch review to identify adverse trends
• Trigger-based requalification (e.g., after significant maintenance, process changes, deviations, or as part of planned periodic review—commonly every 1–3 years based on equipment risk assessment)

Out-of-trend (OOT) or out-of-specification (OOS) results, process deviations, or CAPA-resolved issues should all feed directly into decisions regarding early or expanded requalification activities.

SOPs, Training, Preventive Maintenance, Calibration, and Spares

Robust standard operating procedures (SOPs) ensure consistent operation, cleaning, maintenance, and sampling of the jet mill. Key SOPs necessary for compliance and continued qualification include:

• Start-up and shutdown procedure
• Operation and process control (including troubleshooting)
• Cleaning and cleaning verification/validation
• Sampling and documentation
• Changeover and cross-contamination prevention
• Preventive maintenance and calibration schedules
• Parts inventory and management of essential spares (e.g., jets, filters, seals)

Operator training must be documented and regularly assessed, especially after procedural or equipment updates. Preventive maintenance and calibration should follow a pre-defined schedule based on OEM recommendations, criticality, and historical performance data. Calibration of critical sensors (pressure, temperature, particle size analyzers) must be verified prior to PQ and on a scheduled basis thereafter, ensuring data integrity and traceability.

Change Control, Deviations, and CAPA Linkage

Requalification of the jet mill is often triggered by changes such as process parameter updates, critical component replacements, software/automation changes, or significant deviations impacting prior validated state. All changes must be evaluated through a formal change control process, with risk assessments to determine impact, requalification scope, and documentation requirements.

All deviations encountered during operation, cleaning, PQ, or continued use must be recorded, investigated, and assessed for product impact. If root cause analysis and CAPA indicate a potential or actual loss of validated state, partial or full requalification becomes mandatory.

Validation and Requalification Deliverables

Comprehensive documentation is essential for audit readiness and ongoing compliance. Each requalification cycle should generate or update the following:

• PQ Protocol: Clearly defining objective, scope, methodology, test parameters, sampling plans, acceptance criteria, responsibilities, and data recording formats.
• PQ Report: Detailed documentation of executed steps, raw and summarized results, any deviations or changes, and conclusions on equipment suitability.
• Traceability Matrix: Mapping protocol requirements and acceptance criteria to observed results and conclusions for clear audit trails.
• Summary Report: Synthesizing findings, conclusions, and recommendations; confirming reestablished validated state and highlighting ongoing monitoring/control actions.

Frequently Asked Questions (FAQ)

What triggers jet mill requalification?

Common triggers include major repairs or component changes, process parameter changes, unsuccessful performance in ongoing monitoring, cleaning validation failures, or at predetermined periodic intervals per the site’s validation policy.

Is worst-case testing mandatory for jet mill PQ during requalification?

Yes, worst-case conditions must be included to demonstrate equipment suitability under maximum challenge scenarios, such as the smallest or largest batches and hardest-to-mill products.

How does jet mill PQ relate to cleaning validation?

PQ outcomes must show that the jet mill can be adequately cleaned and that cleaning procedures consistently prevent cross-contamination between products. Cleaning verification or validation is closely tied to PQ sampling and acceptance criteria.

How often should the jet mill be requalified?

Requalification frequency is risk-based, usually every 1–3 years, or in response to significant changes, deviations, cleaning failures, or as guided by trend analyses.

What documentation should be maintained for jet mill requalification?

Essential documents include approved PQ protocols and reports, executed sampling plans, raw data, cleaning verification records, change control and CAPA documentation, and a traceability matrix.

Who should be involved in jet mill requalification activities?

A cross-functional team comprising QA, production, engineering, validation, and sometimes analytical laboratory personnel should collaborate on protocol development, execution, result review, and approval.

What steps are taken if critical PQ acceptance criteria are not met?

Deviations are documented and investigated. Root causes are determined and corrective or preventive actions implemented. Additional PQ runs or expanded requalification may be required until all acceptance criteria are satisfied.

Is operator training required post-requalification?

Yes, all relevant personnel must be retrained on any changed procedures or equipment features following requalification before returning the jet mill to routine GMP operation.

Conclusion

Jet mill requalification is a critical component of the equipment validation lifecycle in the manufacture of oral solid dosage forms. A well-structured PQ strategy—encompassing routine and worst-case conditions, robust cleaning and cross-contamination controls, and continued process verification—ensures sustained product quality, regulatory compliance, and patient safety. By maintaining comprehensive SOPs, periodic training, rigorous change management, and thorough documentation, manufacturers can confidently demonstrate a validated state for their jet mills, adapting to both operational needs and evolving regulatory expectations.