Please tell us how you plan to use this document by answering two quick questions. This information will help IASP determine how the curricula are being used. Thank you for your support of this effort.
*IASP members: Please log in to answer the survey.
Nonmembers: Please create a web account to answer the survey.
Task Force Members
Helen Slater and Kathleen Sluka, cochairs; Marie Hoeger Bement, Anne Söderlund
Competency Domains and learning objectives
I. Multidimensional Nature of Pain
II. Pain Assessment and Measurement
III. Management of Pain
IV. Clinical Conditions
The widespread prevalence of pain demonstrates the need for comprehensive pain education for all health-care professionals. Yet not all require the same type of pain-related knowledge and skills. IASP encourages all physiotherapy/physical therapy programs to utilize the following curriculum outline to embed pain education and training. As with other health professions, an objective of curricula is to instill the knowledge and skills necessary to advance the science and management of pain as part of an interprofessional team. The desired outcomes of education emphasize critical competencies that support the humanistic aspects of health care and the learner’s capacity to successfully carry out tasks in the real world. The fundamental concepts and complexity of pain include how pain is observed and assessed, collaborative approaches to treatment options, and application of pain competencies across the lifespan in the context of various settings, populations, and care-team models.
Pain is one of the most common reasons people seek care from physiotherapists/physical therapists. Typically, pain associated with acute tissue injury, infection, and trauma is short-lived and in many cases, resolves. What is not well understood is why following an initial injury, pain can persist or become recurrent in some people and not in others. Additionally, in some cases pain is puzzling, as it appears to start without a clear initiating injury or physical trauma.
Pain is always subjective and always real. While a person’s pain experience is not visible to the observer, this does not indicate that pain is imaginary. The nature of the relationship between tissue insult, injury, and pain is variable, with a number of contextual factors contributing to the experience of pain. These include biological, physical, psychological, occupational, social, cultural, and environmental factors.
The primary therapeutic objective of physiotherapists/physical therapists working with people experiencing pain is to provide evidence-based person-centered care that promotes health and well-being across the lifespan. Person-centered means designing health systems around the needs of people instead of diseases and health institutions, so that everyone (community and individuals) gets the right care, at the right time, in the right place. In this context, the revised curriculum is aligned to the World Health Organization’s Framework for Integrated People-Centered Health Services (language, principles and health-system elements) and the International Classification of Functioning, Disability, and Health (ICF).
Promoting well-being means improving function and encouraging active self-management through the use of physical, cognitive, and behavioral approaches to help reduce the impact of pain and disability. Physiotherapists/physical therapists have a role to provide contemporary education about pain and to encourage early engagement of every patient in appropriate evidence-based active pain-management strategies (what the patient can do themselves), rather than solely focusing on the use of passive interventions (what you do for the patient). In this regard, treatment interventions need to be designed to form part of an overall pain-management approach at the core of which lies self-management.
Physiotherapists/physical therapists can support improved health outcomes using strategies to assist early and appropriate return to functional and meaningful activities while recognizing those patients with complex pain who may require a more interdisciplinary approach to management. In order to achieve this objective, physiotherapists/physical therapists must understand the multidimensional nature of pain, acknowledging the complex factors that underpin each individual’s experience of pain. Knowledge alone is insufficient: therapists also require competencies that underpin the effective and safe delivery of contemporary pain assessments and evidence-based pain treatments and management.
While physiotherapists/physical therapists are not responsible for pharmacological management in most care settings, they should have sufficient knowledge about the use of pharmacological agents for pain management and understand their risks and benefits. Physiotherapists/physical therapists should be competent in utilizing a “therapeutic window” created by pharmacological agents, to encourage the use of active management strategies, as appropriate, for each individual person.
Who is the curriculum intended for?
This curriculum is appropriate for pre-licensure physiotherapy/physical therapy students, but it also is more widely applicable. “Pre-licensure education” refers to the training period prior to obtaining initial licensure to practice in the chosen profession. Pre-licensure education was chosen because it represents the foundational period of entry-level professional education; however, application of these competencies is relevant to clinical learners well beyond pre-licensure training (e.g., post-licensure training or continuing education).
Is the curriculum designed for global use?
Considerable variation exists from country to country in the academic structure of professional programs for physiotherapy/physical therapy and in the professional expectations that are made of an entry-level therapist. Further, the burden of disease and health priorities vary across the developing and developed world.
Consensus-derived competencies across four key domains have been developed to be relevant and applicable across all settings (low, middle, and high-income countries and resourcing). The specific learning objectives and outcomes underpinning these domains are intentionally designed to be flexible, allowing for adaptation that accommodates specific health settings or resourcing. Therefore, the curriculum can be integrated within programs using whatever structural, regulatory, and educational approaches are deemed the most appropriate to meet local professional and program needs and the health priorities of that setting.
It is recommended that where possible, the curriculum should be taught as a discrete unit, with content and competencies horizontally and vertically aligned to other units of study such as physiology, anatomy, kinesiology, orthopedics, manual therapy, or physical agents. Further, we recommend that as far as possible, the curriculum is delivered by educators and clinical supervisors with formal academic qualifications that include a background in pain science.
Moving from knowledge to competencies
What is happening?
IASP is reorienting all curricula towards competency-based education because educational goals (in the form of agreed-upon competencies) are important for achieving the long-term objective of improving the delivery of pain care, and incorporating pain competencies into the metrics used to assess both institutions and graduates by regulatory and accrediting bodies could lead to lasting improvements in pain education.
Why is this happening?
Learning objectives often focus on what a learner should know (knowledge-based curriculum), whereas competency-based education also focuses on what the learner should be able to do. Competency-based education (CBE) emphasizes the learner’s capacity to carry out tasks successfully in the real world. CBE focuses on the desired performance characteristics of health-care professionals, as opposed to what or how learners are taught. Thus, CBE shifts the metrics for judging the effectiveness of educational programs toward assessing the practical impact of education, instead of simply its content or process.
How have the competency domains been derived?
An interprofessional executive committee led a consensus-building process to develop these core competencies for pre-licensure health professional education. Consensus-derived competencies were categorized within four domains:
- Multidimensional nature of pain
- Pain assessment and measurement
- Management of pain
- Pain conditions
These domains address the fundamental concepts and complexity of pain; how pain is observed and assessed; collaborative approaches to treatment options; and application of competencies across the life span in the context of various settings, populations, and care-team models. A set of values and guiding principles are embedded within each domain.
The final list included 21 pain assessment and management core competencies under four domains.
How is this curriculum structured?
This document uses a hierarchical structure:
- Learning outcomes
- Competencies (four domains, each with guiding principles and specific learning objectives)
The physical therapy curriculum guidelines are evidence-based. The evidence to support these guidelines is outlined in Pain Mechanisms and Management of Pain for Physical Therapists, KA Sluka (ed), IASP Press/Wolters-Kluwer, 2016.
The following principles inform the curriculum development for entry-level physical therapists. These principles are drawn from key documents including the Declaration of Montréal (IASP 2010) and pain competencies (Fishman et al. 2013):
Article 1. The right of all people to have access to pain management without discrimination
Article 2. The right of people in pain to acknowledgment of their pain and to be informed about how it can be assessed and managed
Article 3. The right of all people with pain to have access to appropriate assessment and treatment of the pain by adequately trained health care professionals
Following are principles that guide a physiotherapist’s/physical therapist’s person-centered pain care and align with the Declaration of Montreal:
- Pain is a dynamic and complex experience that involves the interaction of biological, physical, psychological, social, and environmental factors that are specific to each individual.
- Pain may be acute, acute on chronic, recurrent, chronic/persistent, and occur at any stage across the lifespan.
- Pain assessment, treatment, and management are influenced by cultural, institutional, social, and regulatory factors.
- Pain must be assessed in a comprehensive, safe, ethical, and consistent manner using valid and reliable assessment tools and outcome measures that help inform prognosis-making with consideration of risks, benefits, costs, and limitations of interventions.
- Physiotherapists/physical therapists should demonstrate empathic and compassionate patient communication when establishing person-centered pain-related goals and supporting self-management strategies.
- Comprehensive pain management should be underpinned by sound theoretical models and empirical evidence and facilitate active involvement of the patient in developing lifelong healthy pain behaviors.
- The physiotherapist/physical therapist is an essential member of the pain-management team and advocates for an individualized pain-management plan that integrates the perspectives of patients, social support systems, and team members.
Upon completion of this pain curriculum, the entry-level physiotherapist/physical therapist will be able to achieve the following learning outcomes.
- Understand and explain the biopsychosocial model and its relevance to pain, one’s response to pain, and the impact of pain on one’s life.
- Apply knowledge of basic science of pain to person-centered assessment and management of pain.
- Promote health and well-being through reducing the impact of pain and disability.
- Assess or measure the biological, physical, and psychosocial factors that contribute to pain, impairment, and disability using valid and reliable assessment tools.
- Identify professional, system, patient, family, and community barriers to effective pain assessment and management.
- Develop an evidence-based management program in collaboration with the client/patient, directed at modifying pain and encouraging helpful behaviors, promoting tissue healing, improving function, reducing disability, and facilitating recovery.
- Implement management that includes patient education, active approaches such as functionally oriented behavioral-movement reeducation approaches and exercise), passive approaches such as manual therapy (where indicated and avoiding erroneous and potentially catastrophic rationales such as “realignment,” “stabilizing,” “correcting”), and the application of electro-physical agents as indicated.
- Demonstrate an awareness of their scope of practice to evaluate and manage patients experiencing pain using evidenced-based treatment and management.
- Demonstrate awareness of other professionals’ skills and competencies to enable appropriate and timely collaboration and on referral.
- Communicate appropriate information to other health professionals involved in providing patient care to optimize interdisciplinary management, including medical and surgical, behavioral and psychological, or pharmacological approaches.
- Recognize individuals who are at risk for under-treatment of their pain (e.g., individuals who are unable to self-report pain, neonates, and cognitively impaired individuals) or populations where care disparities exist.
- Practice in accordance with an ethical code that recognizes human rights, diversity, and the requirement to “do no harm.”
- Reflect critically on effective ways to work with and improve care for people with pain.
- Regularly update personal knowledge of pain science and evidence-based pain management.
Curriculum competencies and learning objectives
Competency Domain 1: Multidimensional Nature of Pain
What is pain? This domain focuses on the fundamental concepts of pain including the science, nomenclature, and experience of pain, and pain’s impact on the individual and society.
- Explain the complex, multidimensional, and individual-specific nature of pain.
- Present theories and science for understanding pain.
- Define terminology for describing pain and associated conditions.
- Describe the impact of pain on society.
- Explain how cultural, institutional, societal, and regulatory influences affect assessment and management of pain.
Domain 1 Learning Objectives/Activities
- Define and explain pain to others (patients, people, community, colleagues) as a complex, multidimensional experience.
- Recognize the inter-individual variability in pain presentations and apply this understanding to contextualize the assessment and management of pain considering age, sex, family, and culture.
- Special attention should be paid to pain across the lifespan from the infant to the older adult
- Attention should be paid to cultural influences on pain
- Effects of sex and gender on pain and pain management should be considered
- Influence of the pain experience on the family, and the family on the pain experience, are critical to effective assessment and management
- Explain the current theories and science of pain that considers anatomical, physiological, psychological, and social factors of pain and pain management. Specifically:
- Understand and describe the neurological pathways from the nociceptor to the cortex, how these pathways are unique to different tissue types (i.e., skin, muscle, joint, viscera), and the different pathways involved in the processing and modulating nociceptive information and pain experience
- Understand peripheral, spinal, and central sensitization processes, how these forms of plasticity are associated with nociception and pain perception, and the implications for assessment, treatment, and management
- Recognize and describe the mechanistic descriptors for the clinical classification of pain (nociceptive, nociplastic, and neuropathic)11
- Characterize and apply the mechanisms that underlie specific biopsychosocial aspects of nociception and pain: e.g., referred pain, primary hyperalgesia, secondary hyperalgesia, allodynia
- Discuss the role of ion channels, neurotransmitters, molecular pathways, and non-neuronal cells/systems (e.g., immune) in nociceptive processing from the peripheral and central nervous system and explain how these processes may contribute to pain
- Characterize the central nervous system pathways that modulate nociceptive transmission and appraise how these systems may contribute to pain
- Recognize neuroimaging tools and describe key brain regions and connections potentially involved in pain
- Establish the cognitive and emotional state of the individual and explain how this can influence pain
- Discuss the complex changes that can occur in motor function in association with pain and describe how a plan of care would be individualized to address unhelpful movement behaviors (e.g., fear-avoidance)
- Describe the magnitude of the problem of pain as a public health problem that includes social, ethical, and economic consequences.
- Describe how institutional, societal, and regulatory factors influence the assessment, treatment, and management of pain.
Competency Domain 2: Pain Assessment and Measurement
How is pain recognized? This domain relates to how pain is assessed, quantified, and communicated, as well as how the individual, the health system, and society affect these activities.
- Use valid and reliable tools for measuring pain and associated symptoms to assess and reassess related outcomes as appropriate for the clinical context and population.
- Identify and analyze patient, provider, and system factors that can facilitate or interfere with effective pain assessment.
- Assess patient preferences and values to determine pain-related goals and priorities.
- Demonstrate empathic and compassionate communication during pain assessment.
Domain 2 Learning Objectives/Activities
- Critically evaluate and apply reliable and valid pain assessment measures that examine:
- Pain intensity/severity (e.g., Numerical Rating Scale, Visual Analogue Scale, Brief Pain Inventory, Location, Type, including nociceptive, nociplastic, and neuropathic
- Function and Disability/Impairment (e.g., Six-minute Walk Test, Oswestry Disability Index, Örebro Musculoskeletal Pain Questionnaire)
- Psychophysical (pain thresholds) or autonomic response measures (e.g., skin conductance)
- Psychological factors (e.g., Pain Catastrophizing Scale, Fear Avoidance Scale, depression, anxiety, Stress Scale, Pain Self-Efficacy Questionnaire)
- Social domain (e.g., supportive social network, Pain Disability Index)
- Person-centered factors (identified by a thorough clinical interview; e.g., sex, age, culture, beliefs about pain, expectations, coping strategies, impact)
- Vulnerable populations (e.g., communication barriers, cognitive impairment, cultural sensitivities)
- Social factors (e.g., supportive network, participation in life)
- Identify and analyze social, environmental (work/home) and institutional context or factors unique to the person that can impact the assessment of pain.
- Use a person-centered approach to identify patient priorities and pain-related goals across the biopsychosocial domain.
- Identify and analyze the differences between acute, acute-on-chronic, recurrent, and chronic pain and the implications of these for pain assessment.
- Interpret, critically appraise (reliability, validity, and responsiveness), and implement available screening measures for:
- Risk factors for the development of chronic pain conditions
- Identifying subgroups of responders/nonresponders in transition from acute to chronic pain
- Monitor the effects of pain management at set time points (e.g., first visit, at timely points during treatment, and at the end of treatment) using validated screening tools and appropriate outcomes measures and adjust the management plan as needed.
- Understand and apply an empathetic and person-centered communication in assessment.
Competency Domain 3: Management of Pain
This domain focuses on collaborative approaches to decision making, diversity of treatment options, the importance of patient agency, risk management, flexibility in care, and treatment based on appropriate understanding of the clinical condition.
- Demonstrate the inclusion of patient and others, as appropriate, in the education and shared decision-making process for pain care.
- Identify pain treatment options that can be accessed in a comprehensive pain-management plan.
- Explain how health promotion and self-management strategies are important to the management of pain.
- Develop a pain-treatment plan based on benefits and risks of available treatments.
- Monitor effects of pain management approaches to adjust the plan of care as needed.
- Differentiate physical dependence, substance use disorder, misuse, tolerance, addiction, and non-adherence.
- Develop a treatment plan that takes into account the differences between acute pain, acute-on-chronic pain, chronic/persistent pain, and pain at the end of life.
Domain 3 Learning Objectives/Activities
- Develop a person-centered, evidence-based pain-management plan applying goals that are specific, measurable, achievable, relevant, and time-framed.
- Develop and implement a management plan that reflects meaningful shared decision making, including the person and relevant others (such as family, friends, health professionals)
- Undertake shared decision making (with the patient) that is underpinned by sound clinical reasoning and contemporary pain science
- Recognize the impact of and evidence for the use of education and self-management as key components of person-centered pain management.
- Facilitate person-focused learning and understanding that it is based on available science (theoretical models/frameworks, educational science), using available resources (eHealth, telehealth, one-on-one, group based) and is cognizant of age, gender, culture, and health literacy while relevant to specific conditions, lifespan, and care settings
- Identify critical misconceptions held by patients about their pain, the likely contributors to it, and appropriate science-based treatments
- Identify tailored target concepts that will facilitate person-centered engagement in a self-management biopsychosocial approach to recovery
- Understand and implement conceptual change strategies that support and reinforce behavior change
- Provide learning aids and resources using various media to augment and facilitate the embedding and reinforcement of behavior change
- Evaluate the effectiveness of behavior change strategies as they relate to each target concept
- Communicate pain concepts and principles to individuals in a way they understand and that empowers effective self-management
- Understand, identify, and implement appropriate and available evidence-based treatment and management options to support person-centered pain management.
- Understand, identify, and implement a pain-management plan that supports early recovery and reflects the unique multidimensional nature of pain in each individual and that addresses all the relevant dimensions of pain for that person within their given context (work, school, home, care setting)
- Consider when an opinion is indicated from other health professionals for the use of multimodal treatments, including but not limited to nonpharmacological, pharmacological, and surgical procedures or interventions
- Be cognizant of the use of digital health resources when appropriate and where other resources are limited or inaccessible (e.g., online pain interventions and educational, cognitive, and behavioral interventions)
- Understand and communicate the requirement for input from other health professionals as appropriate to best meet person-centered needs
- Apply evidence-based, person-centered self-management strategies for pain that promote a person’s general well-being.
- Understand and explain how self-management strategies can promote better health and well-being
- Implement self-management strategies based on current science of pain, education, neuroscience, and behavior change to support improved outcomes and adherence
- Educate and support the person to adopt active rather than solely passive pain-management strategies (things people do for themselves, as opposed to things done for or to the person)
- Identify and manage potential benefits and risks associated with person-centered management plans.
- Understand comorbidities as risk factors
- Consider and explain the range of evidence-based pain treatments options that could provide greatest benefit while minimizing risk
- Recognize the differences between physical dependence, substance-use disorder, misuse, tolerance, addiction, and non-adherence.
- Develop a treatment plan based on the differences between acute, acute-on-chronic, recurrent, and chronic pain and pain across the lifespan.
- Identify and implement exercise and activity as a key component of physiotherapy/physical therapy management, including across all stages of pain conditions and across the lifespan.
- Understand why exercise is beneficial and explain to patients and reassure them that their capacity for exercise will improve as they transition from sedentary behaviors to more active behaviors (e.g., the transition in muscle-based receptors)
- Develop and implement an exercise prescription that is meaningful to the person and that is achievable
- Develop and implement an exercise prescription using appropriate exercise dose parameters (mode, frequency, duration, and intensity)
- Evaluate and adjust the exercise prescription based on contextual factors (age, condition, comorbidities, health status, risk/benefit factors, fear avoidance/endurance, unhelpful beliefs, and hurt and harm)
- Implement motivational strategies and adherence techniques to support compliance with exercise behaviors (e.g., use of apps, biofeedback, pacing charts)
- Identify mechanisms of action for exercise and understand how these can influence the choice of exercise program
- Evaluate outcomes from exercise and activity-based management
- Identify the indications and evidence for and the proposed mechanisms underlying commonly used interventions, including but not limited to exercise, manual therapy, relaxation strategies (breathing, body scan), mindfulness meditation, and electrotherapeutic agents such as TENS and interferential current, acupuncture, ultrasound, laser, and biofeedback.
- Identify the indications and evidence for the use of appropriate physiotherapy/physical therapy management.
- Apply cognitive and behavioral approaches to support improved functional movement and person-centered pain outcomes (e.g., specifically addressing beliefs and fear avoidance or endurance).
- Understand the indications, evidence, and proposed mechanisms for pharmacologic agents for pain management (e.g., non-opioid medication, selective (COX2) and nonselective nonsteroidal anti-inflammatory drugs, gabapentinoids, reuptake inhibitors), opioid analgesia (weak and strong), as well as co-analgesics and topical analgesics.
Competency Domain 4: Pain Conditions
Clinical conditions: How does context influence pain management? This domain focuses on the role of the clinician in the application of the competencies developed in domains 1–3 and in the context of varied patient populations, settings, and care teams.
- Describe the unique pain assessment and management needs of special populations.
- Explain how to assess and manage pain across settings and transitions of care.
- Describe the role, scope of practice, and contribution of the different professions within a pain-management care team.
- Implement an individualized pain-management plan that integrates the perspectives of patients, their social support systems, and health-care providers in the context of available resources.
- Describe the role of the clinician as an advocate in assisting patients to meet treatment goals.
Domain 4 Learning Objectives/Activities
- Identify individuals, conditions (e.g., musculoskeletal, neurological, cancer) and specific populations at risk for under-treatment of their pain (e.g., individuals who are unable to self-report pain, neonates, cognitively impaired, adolescents transitioning to adult care, older age groups, elite forces, elite sports people, veterans, cultural minorities) and develop an appropriate plan of care.
- Recognize and implement a high-value pain-management plan and reduce the use of low-value pain management.
- Understand how to assess and manage people with pain across different pain settings and transitions of care (hospital, private practice, nursing home, hospice).
- Identify the roles and responsibilities of other health-care professionals in the area of pain management.
- Understand the limitations and scope of physiotherapy/physical therapy practice and how other health professionals contribute to pain management
- Describe the indications for multimodal, multidisciplinary, or interdisciplinary management
- Communicate with other health professionals about assessment and management of pain
- Develop and implement an individualized management plan based on patient preferences and available resources.
- Describe and apply methods that support a strong therapeutic relationship that enhances patient self-management, compliance, and adherence.
- Recognize and describe the role of the clinician to advocate for and assist the patient in setting treatment goals.
- Identify and address the positive and negative influences of the clinician’s beliefs and language about pain on outcomes and adherence (including but not limited to diagnosis, assessment findings, imaging, treatment, and prognosis).
Thank you to the members of the External Reference Group for providing valuable feedback on the final curriculum: Joel Bialowsky (USA), Carol Courtney (USA), Ben Darlow (New Zealand), Mary Beth Geiser (USA), Steve George, USA, Morten Hogh (Denmark), Ivan Huijnen (Netherlands), Julia Hush (Australia), Mari Lundberg (Sweden), Takako Matsubara (Japan), Lorimer Moseley (Australia), Thorvaldur Palsson (Denmark), Romy Parker (South Africa), Josimari Melo de Santana (Brazil).
References and Endnotes
 In this document, the terms physiotherapist and physical therapist are both used to acknowledge regional differences
 A person is always a person and sometimes a patient
 World Health Organization Framework for Integrated People-Centered Health Services takes a renewed focus on service delivery through an integrated and people-centered lens. This is critical for reaching underserved and marginalized populations to ensure that no one is left behind. http://www.who.int/servicedeliverysafety/areas/people-centred-care/framework/en/
 World Health Organization: www.youtube.com/watch?v=pj-AvTOdk2Q
 ICF is a multipurpose classification intended for a wide range of uses in different sectors. ICF is WHO’s framework for health and disability. It is the conceptual basis for the definition, measurement, and policy formulations for health and disability. It is a universal classification of disability and health for use in health and health-related sectors. It is a classification of health and health-related domains: domains that help us describe changes in body function and structure, what a person with a health condition can do in a standard environment (their level of capacity), as well as what they actually do in their usual environment (their level of performance). www.who.int/classifications/icf/en/
 Fishman et al. Core Competencies for Pain Management: Results of an Interprofessional Consensus Summit, Pain Medicine 2013; 14: 971–981
 Gruppen LD, Mangrulkar RS, Kolars JC. The promise of competency-based education in the health professions for improving global health. Hum Resour Health 2012;10(1):43.
 Fishman et al. Core Competencies for Pain Management: Results of an Interprofessional Consensus Summit, Pain Medicine 2013; 14: 971–981
 Learning outcomes are statements that describe/list measurable skills, competencies, and knowledge that students have achieved and can demonstrate upon successfully completing a course of study
 Learning objectives/activities describe what the learner should be able to achieve at the end of a learning period. Note: in this document, learning objectives do not match competencies one-for-one. For some competencies, there are multiple learning objectives. These learning objectives have been developed to address specific requirements for physiotherapists/physical therapists.
11 International Association for the Study of Pain Taxonomy: https://www.iasp-pain.org/resources/terminology/
© Copyright 2018 International Association for the Study of Pain. All Rights Reserved. No part of these materials may be reproduced in any form or by any means without the express written permission of the International Association for the Study of Pain. The unauthorized reproduction or distribution of these copyrighted materials is illegal and may result in civil or criminal penalties under the U.S. Copyright Act and applicable copyright laws.