EFFECTIVE/PUBLICATION DATE: 07/02/96
SSR 96-9p: POLICY INTERPRETATION RULING
TITLES II AND XVI:
DETERMINING CAPABILITY TO DO OTHER WORK--IMPLICATIONS OF A RESIDUAL
FUNCTIONAL CAPACITY FOR LESS THAN A FULL RANGE OF SEDENTARY WORK
PURPOSE: To explain the Social Security Administration's policies regarding the impact of a residual functional capacity (RFC) assessment for less than a full range of sedentary work on an individual's ability to do other work. In particular, to emphasize that:
- An RFC for less than a full range of sedentary work reflects very serious limitations resulting from an individual's medical impairment(s) and is expected to be relatively rare.
- However, a finding that an individual has the ability to do less than a full range of sedentary work does not necessarily equate with a decision of "disabled." If the performance of past relevant work is precluded by an RFC for less than the full range of sedentary work, consideration must still be given to whether there is other work in the national economy that the individual is able to do, considering age, education, and work experience.
CITATIONS (AUTHORITY): Sections 223(d) and 1614(a) of the Social Security Act (the Act), as amended; Regulations No. 4, sections 404.1513(c), 404.1520, 404.1520a, 404.1545, 404.1546, 404.1560, 404.1561, 404.1562, 404.1563 through 404.1567, 404.1569, 404.1569a; appendix 1 of subpart P, section 12.00; appendix 2 of subpart P, sections 200.00 and 201.00; Regulations No. 16, sections 416.913(c), 416.920, 416.920a, 416.945, 416.946, 416.960, 416.961, 416.962, 416.963 through 416.967, 416.969 and 416.969a.
INTRODUCTION: Under the sequential evaluation process, once it has been determined that an individual is not engaging in substantial gainful activity and has a "severe" medically determinable impairment(s) which, though not meeting or equaling the criteria of any listing, prevents the individual from performing past relevant work (PRW), it must be determined whether the individual can do any other work, considering the individual's RFC, age, education, and work experience.
RFC is what an individual can still do despite his or her functional limitations and restrictions caused by his or her medically determinable physical or mental impairments. It is an administrative assessment of the extent to which an individual's medically determinable impairment(s), including any related symptoms, such as pain, may cause physical or mental limitations or restrictions that may affect his or her capacity to perform work-related physical and mental activities. RFC is assessed by adjudicators at each level of the administrative review process based on all of the relevant evidence in the case record, including information about the individual's symptoms and any "medical source statements"--i.e., opinions about what the individual can still do despite a severe impairment(s)--submitted by an individual's treating source(s) or other acceptable medical source.
RFC is the individual's maximum remaining ability to perform sustained work on a regular and continuing basis; i.e., 8 hours a day, for 5 days a week, or an equivalent work schedule. It is not the least an individual can do, but the most, based on all of the information in the case record. The RFC assessment considers only those limitations and restrictions that are caused by an individual's physical or mental impairments. It does not consider limitations or restrictions due to age or body habitus, since the Act requires that an individual's inability to work must result from the individual's physical or mental impairment(s). (See SSR 96-8p, "Titles II and XVI: Assessing Residual Functional Capacity in Initial Claims.")
Initially, the RFC assessment is a function-by-function assessment based upon all of the relevant evidence of an individual's ability to perform work-related activities. This RFC assessment is first used for a function-by-function comparison with the functional demands of an individual's PRW as he or she actually performed it and then, if necessary, as the work is generally performed in the national economy.
However, at the last step of the sequential evaluation process, the RFC assessment is used to determine an individual's "maximum sustained work capability" and, where solely non-exertional impairments are not involved, must be expressed in terms of the exertional classifications of work: sedentary, light, medium, heavy, and very heavy work. The rules of appendix 2 of subpart P of Regulations No. 4 take administrative notice of the existence of numerous unskilled occupations within each of these exertional levels. The rules are then used to direct decisions about whether an individual is disabled or, when the individual is unable to perform the full range of work contemplated by an exertional level(s), as a framework for decisionmaking considering the individual's RFC, age, education, and work experience.
The impact of an RFC for less than a full range of sedentary work is especially critical for individuals who have not yet attained age 50. Since age, education, and work experience are not usually significant factors in limiting the ability of individuals under age 50 to make an adjustment to other work, the conclusion whether such individuals who are limited to less than the full range of sedentary work are disabled will depend primarily on the nature and extent of their functional limitations or restrictions. On the other hand, since the rules in Table No. 1 of appendix 2, "Residual Functional Capacity: Maximum Sustained Work Capability Limited to Sedentary Work as a Result of Severe Medically Determinable Impairment(s)," direct a decision of "disabled" for individuals age 50 and over who are limited to a full range of sedentary work, unless the individual has transferable skills or education that provides for direct entry into skilled sedentary work, the impact of an RFC for less than the full range of sedentary work in such individuals is less critical.
POLICY INTERPRETATION: Under the regulations, "sedentary work" represents a significantly restricted range of work. Individuals who are limited to no more than sedentary work by their medical impairments have very serious functional limitations. For the majority of individuals who are age 50 or older and who are limited to the full range of sedentary work by their medical impairments, the rules and guidelines in appendix 2 require a conclusion of "disabled."
Nevertheless, the rules in Table No. 1 in appendix 2 take administrative notice that there are approximately 200 separate unskilled sedentary occupations, each representing numerous jobs, in the national economy. Therefore, even though "sedentary work" represents a significantly restricted range of work, this range in itself is not so prohibitively restricted as to negate work capability for substantial gainful activity in all individuals.
Moreover, since each occupation administratively noticed by Table No. 1 represents numerous jobs, the ability to do even a limited range of sedentary work does not in itself establish disability in all individuals, although a finding of "disabled" usually applies when the full range of sedentary work is significantly eroded (see Using the Rules in Table No. 1 as a Framework: "Erosion" of the Occupational Base below). In deciding whether an individual who is limited to a partial range of sedentary work is able to make an adjustment to work other than any PRW, the adjudicator is required to make an individualized determination, considering age, education, and work experience, including any skills the individual may have that are transferable to other work, or education that provides for direct entry into skilled work, under the rules and guidelines in the regulations.
The ability to perform the full range of sedentary work requires the ability to lift no more than 10 pounds at a time and occasionally to lift or carry articles like docket files, ledgers, and small tools. Although a sedentary job is defined as one that involves sitting, a certain amount of walking and standing is often necessary in carrying out job duties. Jobs are sedentary if walking and standing are required occasionally and other sedentary criteria are met. "Occasionally" means occurring from very little up to one- third of the time, and would generally total no more than about 2 hours of an 8-hour workday. Sitting would generally total about 6 hours of an 8-hour workday. Unskilled sedentary work also involves other activities, classified as "nonexertional," such as capacities for seeing, manipulation, and understanding, remembering, and carrying out simple instructions.
The Occupational Base for Sedentary Work
The term "occupational base" means the approximate number of occupations that an individual has the RFC to perform considering all exertional and nonexertional limitations and restrictions. (See SSR 83-10, "Titles II and XVI: Determining Capability to Do Other Work--The Medical- Vocational Rules of Appendix 2" (C.E. 1981-1985, p. 516).) A full range of sedentary work includes all or substantially all of the approximately 200 unskilled sedentary occupations administratively noticed in Table No. 1.
Thus, the RFC addressed by a particular rule in Table No. 1 establishes an occupational base that at a minimum includes the full range of unskilled sedentary occupations administratively noticed. The base may be broadened by the addition of specific skilled or semiskilled occupations that an individual with an RFC limited to sedentary work can perform by reason of his or her education or work experience. However, if the individual has no transferable skills or no education or training that provides for direct entry into skilled work, the occupational base represented by the rules in Table No. 1 comprises only the sedentary unskilled occupations in the national economy that such an individual can perform.
The rules in Table No. 1 direct conclusions as to disability where the findings of fact coincide with all of the criteria of a particular rule; i.e., RFC (a maximum sustained work capability for sedentary work) and the vocational factors of age, education, and work experience. In order for a rule in Table No. 1 to direct a conclusion of "not disabled," the individual must be able to perform the full range of work administratively noticed by a rule. This means that the individual must be able to perform substantially all of the strength demands defining the sedentary level of exertion, as well as the physical and mental nonexertional demands that are also required for the performance of substantially all of the unskilled work considered at the sedentary level. Therefore, in order for a rule to direct a conclusion of "not disabled," an individual must also have no impairment that restricts the nonexertional capabilities to a level below those needed to perform unskilled work, in this case, at the sedentary level.
Using the Rules in Table No. 1 as a Framework: "Erosion" of the Occupational Base
Where any one of the findings of fact does not coincide with the corresponding criterion of a rule in Table No. 1 (except in those cases where the concept of borderline age applies), the rule does not direct a decision. In cases such as the following, the medical-vocational rules must be used as a framework for considering the extent of any erosion of the sedentary occupational base:
- Any one of an individual's exertional capacities is determined to be less than that required to perform a full range of sedentary work; or
- Based on an individual's exertional capacities, a rule in Table No. 1 would direct a decision of "not disabled," but the individual also has a nonexertional limitation(s) that narrows the potential range of sedentary work to which he or she might be able to adjust (i.e., the individual has the exertional capacity to do the full range of sedentary work, but the sedentary occupational base is reduced because of at least one nonexertional limitation).
When there is a reduction in an individual's exertional or nonexertional capacity so that he or she is unable to perform substantially all of the occupations administratively noticed in Table No. 1, the individual will be unable to perform the full range of sedentary work: the occupational base will be "eroded" by the additional limitations or restrictions. However, the mere inability to perform substantially all sedentary unskilled occupations does not equate with a finding of disability. There may be a number of occupations from the approximately 200 occupations administratively noticed, and jobs that exist in significant numbers, that an individual may still be able to perform even with a sedentary occupational base that has been eroded.
Whether the individual will be able to make an adjustment to other work requires adjudicative judgment regarding factors such as the type and extent of the individual's limitations or restrictions and the extent of the erosion of the occupational base; i.e., the impact of the limitations or restrictions on the number of sedentary unskilled occupations or the total number of jobs to which the individual may be able to adjust, considering his or her age, education, and work experience, including any transferable skills or education providing for direct entry into skilled work. Where there is more than a slight impact on the individual's ability to perform the full range of sedentary work, if the adjudicator finds that the individual is able to do other work, the adjudicator must cite examples of occupations or jobs the individual can do and provide a statement of the incidence of such work in the region where the individual resides or in several regions of the country.
Exertional and Nonexertional Limitations and Restrictions
Exertional capacity addresses an individual's limitations and restrictions of physical strength and defines the individual's remaining ability to perform each of seven strength demands: Sitting, standing, walking, lifting, carrying, pushing, and pulling. An exertional limitation is an impairment-caused limitation of any one of these activities.
Nonexertional capacity considers any work-related limitations and restrictions that are not exertional. Therefore, a nonexertional limitation is an impairment- caused limitation affecting such capacities as mental abilities, vision, hearing, speech, climbing, balancing, stooping, kneeling, crouching, crawling, reaching, handling, fingering, and feeling. Environmental restrictions are also considered to be nonexertional.
Thus, it is the nature of an individual's limitations and restrictions, not certain impairments or symptoms, that determines whether the individual will be found to have only exertional limitations or restrictions, only nonexertional limitations or restrictions, or a combination of exertional and nonexertional limitations or restrictions. For example, even though mental impairments often affect nonexertional functions, they may also limit exertional capacity affecting one of the seven strength demands; e.g., from fatigue or hysterical paralysis. Likewise, symptoms, including pain, are not intrinsically exertional or nonexertional; when a symptom causes a limitation in one of the seven strength demands, the limitation must be considered exertional. (See SSR 96-8p, "Titles II and XVI: Assessing Residual Functional Capacity in Initial Claims.")
Guidelines for Evaluating the Ability to Do Less Than a Full Range of Sedentary Work
The following sections provide adjudicative guidance as to the impact of various RFC limitations and restrictions on the unskilled sedentary occupational base. The RFC assessment must include a narrative that shows the presence and degree of any specific limitations and restrictions, as well as an explanation of how the evidence in file was considered in the assessment. The individual's maximum remaining capacities to perform sustained work on a regular and continuing basis (what he or she can still do 8 hours a day, for 5 days a week, or an equivalent work schedule) must be stated.
An accurate accounting of an individual's abilities, limitations, and restrictions is necessary to determine the extent of erosion of the occupational base, the types of sedentary occupations an individual might still be able to do, and whether it will be necessary to make use of a vocational resource. The RFC assessment must be sufficiently complete to allow an adjudicator to make an informed judgment regarding these issues.
Exertional Limitations and Restrictions
Lifting/carrying and pushing/pulling: If an individual is unable to lift 10 pounds or occasionally lift and carry items like docket files, ledgers, and small tools throughout the workday, the unskilled sedentary occupational base will be eroded. The extent of erosion will depend on the extent of the limitations. For example, if it can be determined that the individual has an ability to lift or carry slightly less than 10 pounds, with no other limitations or restrictions in the ability to perform the requirements of sedentary work, the unskilled sedentary occupational base would not be significantly eroded; however, an inability to lift or carry more than 1 or 2 pounds would erode the unskilled sedentary occupational base significantly. For individuals with limitations in lifting or carrying weights between these amounts, consultation with a vocational resource may be appropriate.
Limitations or restrictions on the ability to push or pull will generally have little effect on the unskilled sedentary occupational base.
Standing and walking: The full range of sedentary work requires that an individual be able to stand and walk for a total of approximately 2 hours during an 8-hour workday. If an individual can stand and walk for a total of slightly less than 2 hours per 8-hour workday, this, by itself, would not cause the occupational base to be significantly eroded. Conversely, a limitation to standing and walking for a total of only a few minutes during the workday would erode the unskilled sedentary occupational base significantly. For individuals able to stand and walk in between the slightly less than 2 hours and only a few minutes, it may be appropriate to consult a vocational resource.
Sitting: In order to perform a full range of sedentary work, an individual must be able to remain in a seated position for approximately 6 hours of an 8-hour workday, with a morning break, a lunch period, and an afternoon break at approximately 2-hour intervals. If an individual is unable to sit for a total of 6 hours in an 8-hour work day, the unskilled sedentary occupational base will be eroded. The extent of the limitation should be considered in determining whether the individual has the ability to make an adjustment to other work. See Alternate sitting and standing below.
The fact that an individual cannot do the sitting required to perform the full range of sedentary work does not necessarily mean that he or she cannot perform other work at a higher exertional level. In unusual cases, some individuals will be able to stand and walk longer than they are able to sit. If an individual is able to stand and walk for approximately 6 hours in an 8-hour workday (and meets the other requirements for light work), there may be a significant number of light jobs in the national economy that he or she can do even if there are not a significant number of sedentary jobs.
Alternate sitting and standing: An individual may need to alternate the required sitting of sedentary work by standing (and, possibly, walking) periodically. Where this need cannot be accommodated by scheduled breaks and a lunch period, the occupational base for a full range of unskilled sedentary work will be eroded. The extent of the erosion will depend on the facts in the case record, such as the frequency of the need to alternate sitting and standing and the length of time needed to stand. The RFC assessment must be specific as to the frequency of the individual's need to alternate sitting and standing. It may be especially useful in these situations to consult a vocational resource in order to determine whether the individual is able to make an adjustment to other work.
Medically required hand-held assistive device: To find that a hand-held assistive device is medically required, there must be medical documentation establishing the need for a hand-held assistive device to aid in walking or standing, and describing the circumstances for which it is needed (i.e., whether all the time, periodically, or only in certain situations; distance and terrain; and any other relevant information). The adjudicator must always consider the particular facts of a case. For example, if a medically required hand-held assistive device is needed only for prolonged ambulation, walking on uneven terrain, or ascending or descending slopes, the unskilled sedentary occupational base will not ordinarily be significantly eroded.
Since most unskilled sedentary work requires only occasional lifting and carrying of light objects such as ledgers and files and a maximum lifting capacity for only 10 pounds, an individual who uses a medically required hand-held assistive device in one hand may still have the ability to perform the minimal lifting and carrying requirements of many sedentary unskilled occupations with the other hand. For example, an individual who must use a hand-held assistive device to aid in walking or standing because of an impairment that affects one lower extremity (e.g., an unstable knee), or to reduce pain when walking, who is limited to sedentary work because of the impairment affecting the lower extremity, and who has no other functional limitations or restrictions may still have the ability to make an adjustment to sedentary work that exists in significant numbers. On the other hand, the occupational base for an individual who must use such a device for balance because of significant involvement of both lower extremities (e.g., because of a neurological impairment) may be significantly eroded.
In these situations, too, it may be especially useful to consult a vocational resource in order to make a judgment regarding the individual's ability to make an adjustment to other work.
Nonexertional Limitations and Restrictions
Postural limitations: Postural limitations or restrictions related to such activities as climbing ladders, ropes, or scaffolds, balancing, kneeling, crouching, or crawling would not usually erode the occupational base for a full range of unskilled sedentary work significantly because those activities are not usually required in sedentary work. In the SCO, "balancing" means maintaining body equilibrium to prevent falling when walking, standing, crouching, or running on narrow, slippery, or erratically moving surfaces. If an individual is limited in balancing only on narrow, slippery, or erratically moving surfaces, this would not, by itself, result in a significant erosion of the unskilled sedentary occupational base. However, if an individual is limited in balancing even when standing or walking on level terrain, there may be a significant erosion of the unskilled sedentary occupational base. It is important to state in the RFC assessment what is meant by limited balancing in order to determine the remaining occupational base. Consultation with a vocational resource may be appropriate in some cases.
An ability to stoop occasionally; i.e., from very little up to one-third of the time, is required in most unskilled sedentary occupations. A complete inability to stoop would significantly erode the unskilled sedentary occupational base and a finding that the individual is disabled would usually apply, but restriction to occasional stooping should, by itself, only minimally erode the unskilled occupational base of sedentary work. Consultation with a vocational resource may be particularly useful for cases where the individual is limited to less than occasional stooping.
Manipulative limitations: Most unskilled sedentary jobs require good use of both hands and the fingers; i.e., bilateral manual dexterity. Fine movements of small objects require use of the fingers; e.g., to pick or pinch. Most unskilled sedentary jobs require good use of the hands and fingers for repetitive hand-finger actions.
Any significant manipulative limitation of an individual's ability to handle and work with small objects with both hands will result in a significant erosion of the unskilled sedentary occupational base. For example, example 1 in section 201.00(h) of appendix 2, describes an individual who has an impairment that prevents the performance of any sedentary occupations that require bilateral manual dexterity (i.e., "limits the individual to sedentary jobs which do not require bilateral manual dexterity"). When the limitation is less significant, especially if the limitation is in the non-dominant hand, it may be useful to consult a vocational resource.
The ability to feel the size, shape, temperature, or texture of an object by the fingertips is a function required in very few jobs and impairment of this ability would not, by itself, significantly erode the unskilled sedentary occupational base.
Visual limitations or restrictions: Most sedentary unskilled occupations require working with small objects. If a visual limitation prevents an individual from seeing the small objects involved in most sedentary unskilled work, or if an individual is not able to avoid ordinary hazards in the workplace, such as boxes on the floor, doors ajar, or approaching people or vehicles, there will be a significant erosion of the sedentary occupational base. These cases may require the use of vocational resources.
Communicative limitations: Basic communication is all that is needed to do unskilled work. The ability to hear and understand simple oral instructions or to communicate simple information is sufficient. If the individual retains these basic communication abilities, the unskilled sedentary occupational base would not be significantly eroded in these areas.
Environmental restrictions: An "environmental restriction" is an impairment-caused need to avoid an environmental condition in a workplace. Definitions for various workplace environmental conditions are found in the SCO; e.g., "extreme cold" is exposure to nonweather-related cold temperatures.
In general, few occupations in the unskilled sedentary occupational base require work in environments with extreme cold, extreme heat, wetness, humidity, vibration, or unusual hazards. The "hazards" defined in the SCO are considered unusual in unskilled sedentary work. They include: moving mechanical parts of equipment, tools, or machinery; electrical shock; working in high, exposed places; exposure to radiation; working with explosives; and exposure to toxic, caustic chemicals. Even a need to avoid all exposure to these conditions would not, by itself, result in a significant erosion of the occupational base.
Since all work environments entail some level of noise, restrictions on the ability to work in a noisy workplace must be evaluated on an individual basis. The unskilled sedentary occupational base may or may not be significantly eroded depending on the facts in the case record. In such cases, it may be especially useful to consult a vocational resource.
Restrictions to avoid exposure to odors or dust must also be evaluated on an individual basis. The RFC assessment must specify which environments are restricted and state the extent of the restriction; e.g., whether only excessive or even small amounts of dust must be avoided.
Mental limitations or restrictions: A substantial loss of ability to meet any one of several basic work-related activities on a sustained basis (i.e., 8 hours a day, 5 days a week, or an equivalent work schedule), will substantially erode the unskilled sedentary occupational base and would justify a finding of disability. These mental activities are generally required by competitive, remunerative, unskilled work:
- Understanding, remembering, and carrying out simple instructions.
- Making judgments that are commensurate with the functions of unskilled work--i.e., simple work- related decisions.
- Responding appropriately to supervision, co- workers and usual work situations.
- Dealing with changes in a routine work setting.
A less than substantial loss of ability to perform any of the above basic work activities may or may not significantly erode the unskilled sedentary occupational base. The individual's remaining capacities must be assessed and a judgment made as to their effects on the unskilled occupational base considering the other vocational factors of age, education, and work experience. When an individual has been found to have a limited ability in one or more of these basic work activities, it may be useful to consult a vocational resource.
Use of Vocational Resources
When the extent of erosion of the unskilled sedentary occupational base is not clear, the adjudicator may consult various authoritative written resources, such as the DOT, the SCO, the Occupational Outlook Handbook, or County Business Patterns.
In more complex cases, the adjudicator may use the resources of a vocational specialist or vocational expert. The vocational resource may be asked to provide any or all of the following: An analysis of the impact of the RFC upon the full range of sedentary work, which the adjudicator may consider in determining the extent of the erosion of the occupational base, examples of occupations the individual may be able to perform, and citations of the existence and number of jobs in such occupations in the national economy.
EFFECTIVE DATE: This Ruling is effective on the date of its publication in the Federal Register.
CROSS-REFERENCES: SSR 86-8 "Titles II and XVI: The Sequential Evaluation Process" (C.E. 1986, p. 78), SSR 83-10, "Titles II and XVI: Determining Capability to Do Other Work--The Medical-Vocational Rules of Appendix 2" (C.E. 1981-1985, p. 516), SSR 83-12, "Titles II and XVI: Capability to Do Other Work--The Medical-Vocational Rules as a Framework for Evaluating Exertional Limitations Within a Range of Work or Between Ranges of Work" (C.E. 1981-1985, p. 529), SSR 83-14, "Titles II and XVI: Capability to Do Other Work--The Medical-Vocational Rules as a Framework for Evaluating a Combination of Exertional and Nonexertional Impairments" (C.E. 1981-1985, p. 535), SSR 85-15, "Titles II and XVI: Capability to Do Other Work--The Medical- Vocational Rules as a Framework for Evaluating Solely Nonexertional Impairments" (C.E. 1981-1985, p. 543), SSR 96- 8p, "Titles II and XVI: Assessing Residual Functional Capacity in Initial Claims;" Program Operations Manual System, sections DI 24510.001, DI 24510.005, DI 24510.010, DI 24510.050, DI 24515.061, DI 25001.001, DI 25010.001, DI 25020.005, DI 25020.010, DI 25020.015, DI 25025.001 and DI 28005.015; and Hearings, Appeals, and Litigation Law Manual, sections I-2-548 and I-2-550.
 For a detailed discussion of the difference between the RFC assessment, which is an administrative finding of fact, and the opinion evidence called the "medical source statement" or "MSS," see SSR 96-5p, "Titles II and XVI: Medical Source Opinions on Issues Reserved to the Commissioner."
 RFC may be expressed in terms of an exertional category, such as "light," if it becomes necessary to assess whether an individual is able to perform past relevant work as it is generally performed in the national economy. However, without the initial function-by-function accounting of the individual's capacities, it may not be possible to determine whether the individual is able to perform past relevant work as it is generally performed in the national economy because particular occupations may not require all of the exertional and nonexertional demands necessary to perform the full range of work at a given exertional level. See SSR 96-8p, "Titles II and XVI: Assessing Residual Functional Capacity in Initial Claims."
 However, "younger individuals" age 45-49 who are unable to communicate in English or who are illiterate in English and who are limited to even a full range of sedentary work must be found disabled under rule 201.17 in Table No. 1.
 An "occupation" refers to a grouping of numerous individual "jobs" with similar duties. Within occupations (e.g., "carpenter") there may be variations among jobs performed for different employers (e.g., "rough carpenter").
 The regulations specify that this is an approximation. The revised fourth edition of the Dictionary of Occupational Titles and its companion volumes (the DOT, 1991) lists 137 separate occupations. However, the introduction to Volume I explains that the fourth edition of the DOT (1977) "substantially modified or combined with related definitions" several thousand definitions from the third edition. In 1992, we published a notice in the Federal Register explaining that an analysis of the revised fourth edition of the DOT and available data for the then upcoming volume of the Selected Characteristics of Occupations Defined in the Revised Dictionary of Occupational Titles (SCO) showed "that the range of work of which the medical- vocational rules take administrative notice continues to represent more occupations than would be required to represent significant numbers," and that "we have received no significant data or other evidence to indicate that * * * the unskilled occupational base * * * has changed substantially." (See 57 FR 43005, September 17, 1992.) In February 1996, contact with the North Carolina Occupational Analysis Field Center, the organization that compiles the data the Department of Labor uses in the SCO, confirmed that there are no precise updated data but that the regulatory estimate of approximately 200 sedentary unskilled occupations is still valid, because some of the 137 occupations in the current edition of the DOT comprise more than one of the separate occupations of which we take administrative notice.
 See 20 CFR 404.1563(a) and 416.963(a) and SSR 83-10.
 Bilateral manual dexterity is needed when sitting but is not generally necessary when performing the standing and walking requirements of sedentary work.
 At the hearings and appeals levels, vocational experts (VEs) are vocational professionals who provide impartial expert opinion during the hearings and appeals process either by testifying or by providing written responses to interrogatories. A VE may be used before, during, or after a hearing. Whenever a VE is used, the individual has the right to review and respond to the VE evidence prior to the issuance of a decision. The VE's opinion is not binding on an adjudicator, but must be weighed along with all other evidence.