INST > Clients > JISC > ioNW2

An analysis of skill domain concepts underlying two sets of existing National Occupational Standards

Simon Grant, version of 2007-03-14 


The ioNW2 project aims to enable institutions to share information about their learning opportunities so that learners can easily search for suitable courses from a single portal. One aspect of this will be investigation of a means to represent the skills acquired through studying a course so that this can be part of a learner’s search strategy. The work commissioned to investigate methods of representing skills is focused around the National Occupational Standards (NOSs), managed by Sector Skills Councils (SSCs) in the UK. In particular, two SSCs were designated as the focus of this study:

These are among the 25 or 26 SSCs licensed by the Sector Skills Development Agency,  alongside the 21 other standards setting bodies listed on the ukstandards site.

The first package of work involved analysing the nature of what these SSCs have written in the NOSs, going on to develop a relatively high-level mapping, or “ontology”, of the concepts and structures implicit in the NOSs. This is the subject matter of the current document. It does not involve creating conceptual maps (or ontologies) of any particular domain: this is mentioned in the course of this document, but the creation of an effective conceptual map – mapping significant concepts and relationships throughout a domain – is  a demanding task requiring collaboration across the sector, not dissimilar in scope to the creation of the NOSs themselves.

The following document will then proceed to detail an effective and plausible way of representing those structures in a standard way, intended to serve as groundwork for the practical representation of skill and competence concepts, including the NOS content, used in various contexts. The background rationale for this work may be further illuminated by quoting from the relevant Skills for Health web page

“NOS and NWC can help to establish the link between the aims and objectives of an organization, such as a NHS Trust or department or a health provider within the independent sector e.g. Independent Treatment Centre; and what individuals need to be able to achieve. Consequently NOS and NWC are of use in the design of education and training and in the design of qualifications such as National and Scottish Vocational Qualifications and Higher education programmes. They can also be used in the management and development of organisations and individuals, for job design, recruitment, individual and team development, career planning and appraisal. Within the NHS across the UK they can also be used by employers and individuals to meet the demands of the Knowledge and Skills Framework.” 

What is represented in the National Occupational Standards

There are three points which stand out as common among all NOSs examined, and which can serve as the basic points of reference for a more detailed analysis. These are 

These will first be described, before moving on to the other less universal or more particular structures, and other issues arising from these structures. “Item” is not an official term – it is intended as a neutral reference term here. 

The unit

Units are what is found first, at the top level, when looking into the contents of a particular NOS, and it is the basic unit of documentation on the ukstandards site. Every unit has a title, and some kind of descriptive text explaining what the unit is about. Each one also has a code, which appears to be unique within its own NOS. The unit includes a group of related statements specifying what a person should be able to do, and what a person should know, to be able to carry out work in the particular designated occupational area.  The area covered by a single unit is normally small compared to a job profile, in that a particular job function would normally require ability or competence in areas covered by several units.

There are a number of possible rationales for the size of a unit, though no explicit rationale has  been found amongst the NOSs themselves.

  1. A unit may represent the smallest group of abilities which are usually required together. This would mean that the requirements of any relevant job could be effectively and efficiently described by a suitable combination of units. 
  2. A unit may be a convenient size for the relating of evidence that a person has these abilities. 
  3. A unit may be a convenient size for training people in these abiltities. 
  4. A unit may be a convenient size for assessment of the abilities. 

Of these, the first would appear highly appropriate, though difficult to establish. The others may be easier to establish, while being less convincingly justified. It seems probable that there is sufficient similarity between the optimum unit sizes for each purpose, so that the size of a unit appears uncontroversial. The second rationale would be most relevant to portfolios, as they often involve presenting evidence of ability. The third and fourth are relevant to qualifications. NOSs serve as the basis for National Vocational Qualifications, NVQs, and their Scottish counterparts. NVQs normally cover the ground of several units.

Units are found grouped together in NOS documents on the individual SSC sites, and in “suites” on the ukstandards site. Skillset lists 22 NOSs by name, for example “Broadcast journalism”, “Costume”, “Lighting”. most of which have one document detailing all of the relevant units. “Photo imaging and photo processing” however has 4 documents, one comprising common units, and three relating to sub-fields. The NOS documents have varying numbers of units. Broadcast journalism, for instance, has 17 units specific to the field, and 4 shared with other fields. Costume has 19 of its own and 7 shared.

Similarly, the ukstandards site lists 28 Skillset suites, which are largely the same ones as the  equivalent entries in the Skillset NOS documentation. The codes given for the units are usually related to the ones given in the Skillset documentation, but do not necessarily match exactly.

Skills for Health have 52 “completed frameworks”. The topic areas of the frameworks are very diverse, including “Chemotherapy”, “Children's services”, “Decontamination”, “Health Informatics” and “Workforce Planning”. The number of units in a framework ranges from 1 to 646 – though the one with 646, “Healthcare Science”, is flagged as “currently being integrated”. The framework with the next greatest number of units is “Health and Social Care” with 201 units. We can thus see that there is no fixed norm for the number of units included in one NOS document.

Not all Skills for Health “suites” are NOSs shown on the ukstandards site: there were 41 NOS “frameworks” from Skills for Health on the ukstandards site as at 2007-02-09. This is because some of the Skills for health work is done under the title of National Workforce Competences (NWCs) rather than NOSs. At the time of writing there is an intention to transfer the NWCs into NOSs. 

The performance item

Every NOS unit includes some specification of what someone has to be able to do in order to reach the occupational standard in that unit, as a list of performance items. The rubric for the list – a phrase associated with and introducing it – varies. It can be “This is what you have to do”, “This is what you must be able to do”. The Skills for Health NOS performance criteria simply state “You need to:”. In each case, there is a list of statements, often called “performance criteria”, which could be seen either as complete sentences in the imperative  form, or as the continuations of the sentence started with the rubric. For example, the very first one in the Skills for Health set is “obtain consent from the individual before working with them”; the very last is “inform the appropriate person if there are barriers to implementation”. They can be longer. Skillset's Editing E1 performance statement 4 is “review production information, both written and verbal, and accurately identify its implications for the editing process, and the range of potentially suitable editing media and processes”.

The knowledge item

Also included in every NOS unit is some indication of knowledge which is required or expected of a person to meet the standard, as a list of knowledge items. This is presumed to be the knowledge that underlies the required performance. The ways in which knowledge is specified does vary between different NOSs. Within Skills for Health NOSs, knowledge items are given one of several categories: 

In Skillset's Interactive Media NOS, each unit is given a “Knowledge and Understanding” category  introduced as “this is what you must know” and also an “Awareness” category, “this is what you must be aware of”. Most Skillset NOSs have a single group of “Knowledge and Understanding” items, introduced as “this is what you must know”. In the Skills for Health NOSs, the lists of knowledge items are headed by the rubric “You need to apply:”.

Contents for knowledge items vary extremely widely, but generally are phrased as things that one could know, or know about.  An arbitrary one selected from the Skills for Health NOSs reads “A working knowledge of the types of question that children and young people might ask about your work”. One from the Skillset list is “The nature and use of record-keeping systems”. These sentence fragments cannot necessarily be fully understood out of context. Just taking these two examples, the questions children might ask differ between different occupations, and record-keeping systems may also clearly differ across different occupations. This needs to be borne in mind in any formal structures.

There is at least one exception to the way knowledge items are generally presented, which is in the Skills for Health NOS set for Specialist Public Health. Rather than introducing the knowledge items as “you need to apply” they are introduced identically to the performance items, as “You need to”. Thus, one is “Explain how an articulate population perspective can effectively change decisionmaking about health and wellbeing, care services or public policy.” In these cases, it is as if the knowledge is ready-contextualised together with the way in which the knowledge is expected to be used. This would make assessment easier, but goes against the more general and accepted pattern: it makes sense to specify performance items separately from the knowledge which is expected to underpin and inform that performance. 

Other structures

Within the NOS unit documentation, performance items and knowledge items tend not to appear alone, but rather they are grouped into lists. These lists may belong directly to the unit, or the unit can be subdivided into “elements”, to which at least the performance items are attached. 

Where elements have been made part of the structure, they are subdivisions of a unit. They have a title, and a code which is typically the unit code with a decimal point and an extra digit added. They seem to exist chiefly to group together subsets of performance items, and sometimes knowledge items. 

Other features of the various structures to be found in the NOSs will be mentioned in the sections that follow here. 

Overlap, duplication, redundancy and inter-relationship

It is clear from a first perusal that there is extensive repetition, borrowing, and overlap throughout the NOSs. This occurs at several levels. 

Some units are shared between (normally two) SSCs. For example, Skillset shares a suite with LANTRA, the Sector Skills Council for the Environmental and Land-based Sector, called “Animal Training in the Audio Visual Industries”. In such cases, both SSCs will make it clear that the units are shared, and the name of the other SSC with which they are shared. It is understood that in other cases, SSCs can adapt units from other SSCs to the extent that they are seen as being different, though still much of the material may be in common. It may not be so easy to see when this has taken place.

Within the set of one SSC's “suites” or “frameworks”, there can be general purpose units which are relevant to several occupational contexts. Skillset NOSs have 11 common units with codes F1 to F5, concerned with freelance working, and X1 to X6, concerned with general working practice, health and safety. A selection of these units are reproduced in the various relevant documents. The fact they are reproduced rather than referred to lets in the possibility of version control problems, and other clerical errors, or at least requires careful cross-checking. In an electronically-based set, each unit would be described in only one place, and cross-references would be made. It would appear that this duplication results from the attempt to make the unit sets relevant to particular occupations. 

In Skills for Health NOSs, any shared units are not duplicated in the same way as in Skillset documents. Instead, each “framework” has its own native NOS units, and “references” other units originating in other frameworks. Thus, there are no specifically common units, but any unit may be referenced across different occupational areas. 

Across units, it is more difficult to clarify the exact amount of duplication between performance and knowledge items. Even if items were described in the same words, it might need domain knowledge to decide whether or not the items were actually equivalent across two units; they would likely not be fully equivalent across different occupational domains. 

Among the Skillset NOSs, there is at least one NOS set where some attempt has been made to harmonise knowledge items across units. This is in the Photo imaging and photo processing NOSs. Each knowledge item there is given a K number which has the same topic as the other knowledge items with the same K number in other units. Often, knowledge items with the same K number are identical across different units. However, sometimes a different range is specified. Thus, in the common unit C2, “establish and maintain positive working relations”, there is the knowledge item:

K7 Workplace policy and practice 

• Workplace objectives, priorities, standards and procedures 

• The range of work carried out in the workplace 

• The working practices existing in the workplace 

In the common unit C1, “contribute to effective performance at work”, K7 is given with the same title, but without the middle bulleted point; while in the digital unit D1 “create original artwork for digital images” K7 again has the same title, but only the first point. 

Skills for Health NOSs do not appear to attempt to do any similar explicit harmonisation, nor do other NOSs within the Skillset domain. Only a detailed and painstaking analysis would reveal just how much duplication there is in these cases. 

Another kind of duplication or overlap comes more typically with performance statements. In Skills for Health units, these are generally factored out into the definition and scope. But in some Skillset units, geared towards assessment, there are statements such as this, taken from Skillset's “Broadcast Media Technology level 4”. 

Work with three of the following types of client to establish their objectives:

• operators 

• production 

• technical staff 

• third parties 

• service provider 

• other stakeholders 

This list appears to be a list of possible types of client, at least in the context of the unit, and could well reappear in other units in the same or a related NOS. If the effort were made to separate out the conceptual mapping aspects of this kind of statement, duplication and inconsistency could be reduced. Whether this is actually worth the effort is a complex issue, dependent on several factors, which will not be explored further here. 

Range and scope

Several units, particularly in Skillset NOSs, share a basic structure of unit overview, performance items and knowledge items. But other units in Skillset NOSs, and all units in Skills for Health NOSs, have some way of indicating a range or scope of the particular skill unit. This is done in different ways. 

In the Skills for Health units, it is done in a consistent way. Particular phrases in the performance or knowledge items are given a range of applicability, under the heading, “Scope”. Taking an arbitrary example, in CHS22, “Perform intravenous cannulation”, “Appropriate member of the team” is associated with “a) registered nurse, b) midwife, c) doctor”. This refers to performance item 4, which is “seek clinical advice and support from an appropriate member of the team when events or risks are beyond your level of competence”. In this way, it is clarified that this unit does not extend to seeking clinical advice and support from an orderly, a student nurse, or a medical researcher. Not that this is likely – but there are other examples where more plausible alternatives are explicitly ruled outside the scope of a unit.

In the Skillset NOSs, the practice is more varied. In the Photo-related units, something similar to the Skills for Health practice is done, but with less formal structure. For an arbitrary example, in Photo unit C5, “receive and progress orders for standard products and services”, the description “this is what the unit covers” includes the paragraph “Orders. Customers may place orders in person, by phone or fax, by post, or on-line, and you must be able to respond to any method of approach. You must be able to complete all workplace order records correctly.” Again, we see an enumeration of possibilities, which can scope the range of the skill described in that unit.

In Skillset's NOS for production accountants, there appears a box for each unit headed “Range of applications”. The box for unit PA1 “record financial information and prepare the production’s accounts” has:


• Asset lists 

• Ledger 

Sources of information 

• Ledger 

• Bank reconciliation 

• Creditors reconciliation 

Discrepancies and unusual features 

• Insufficient data has been provided 

• Inconsistencies within the data 

Adjustments relating to 

• Accruals 

• Prepayments 

Lists of Assets 

• Items owned by the production 

• Items leased/hired by the production 

Again, the same pattern is evident, of terms scoped by a list of what is taken, in the context of the particular NOS unit, to be covered by those terms. 

Scope can also be attached to elements rather than to units. The Skillset NOS, joint with LANTRA, “Animal training in the audio-visual industries” is one example of an NOS where this happens. Clearly, for this to make sense, the items that refer to a range should be ones attached at the element level rather than the unit level. In this case, the scope information performs the same function as the Skills for Health units, in defining the range of some term which occurs in a statement. 

Assessment and qualification

Ranges and scopes can be used to define extents of occupational competence as described above, but they are also vital when defining assessment strategies, and defining the range to be assessed for qualifications at various levels. 

The Skillset web site has this to say on occupational qualifications:

“National Vocational Qualifications (NVQs) and Scottish Vocational Qualifications (SVQs) are occupational qualifications. They are work-related and competence based, and develop skills and competencies that are needed to do a particular job. They are based on national occupational standards (where they are available) and are usually assessed in the work place. They can be taken by full-time employees or by school and college students with a work placement or part-time job that enables them to develop the appropriate skills. There are no age limits and no special entry requirements.” 

The approach to defining NVQs can be simply to specify sets of mandatory and optional NOS units which together are taken to count as fulfilling the conditions of the qualification. That still leaves open the question of how the NOS units should be assessed. This can be filled in by separately-documented assessment strategies. Skillset's strategy for assessment of Photo skills discusses the characteristics of assessors, specifies knowledge areas for external quality control, and makes recommendations to awarding bodies – the SSCs do not themselves award NVQs.

Skillset provides some documents which are clearly aimed at assessment, in that they are labelled with a given level (2, 3, or 4). One example is two documents for Broadcast Media Technology, levels 3 and 4. These read much like other NOS documentation, in that they comprise sets of units, but in these cases the units have a scope section where, for each list of options given, it is specified how many items on that list need to be covered, e.g. “Carry out operational adjustments on three of the following types of equipment” followed by a list of 6 types of equipment. These documents appear somewhat problematic, in that they blur the distinction between the NOSs themselves and the approaches to assessing them. 

Much more could be said about assessment in general, and on a high-level conceptual map for assessment. As assessment is not the only purpose of NOSs, this is not taken up further in this document. 

Conceptual mapping

Range and scope statements, whether or not in the context of assessment, often refer to significant entities or concepts within the occupational domain. A careful reading of the NOSs reveals that similar information is given in several varied ways. 

The Skills for Health NOSs are again more regular than Skillset NOSs in this respect. Alongside the activity scope, many Skills for Health units have a “key words and concepts” section, which are definitions relevant to the occupational domain, needed to clarify some word or phrase in the performance or knowledge items. An arbitrary example is  

“Those significant to the individual: Used here to mean any person whom the individual wishes to involve in their plan of care. This includes a partner, relative and/or friend but may be other members of the community or other workers such as volunteers, other care practitioners, advocate, interpreter, lawyer, religious representative, police or prison officer.”  

Some range information is given in this case, as in other cases, but the intention here appears not so much to define what is in scope and what is out of scope, as to illustrate the range of the term, without either prioritising or excluding any particular members of the sets quoted. 

In Skillset NOSs, conceptual mapping information comes in more varied ways. The range and scope information detailed above has plenty of conceptual mapping implications which could in principle be extracted. In addition to those already mentioned above are Skillset's Set Crafts NOS units, where each element has a “range of work”, set out very similarly to the Skills for Health “Scope” definitions. 

The challenge, with conceptual mapping information, is to assess the importance of it to the purposes for which electronic versions of the NOS information may be used. Does it need to be structured, or is it sufficient to reproduce the information in text form for people to read, to clarify the meanings of the relevant concepts, and the ranges? To the extent to which the information needs to be machine-processed, the conceptual mapping information needs to be formalised – this is discussed below. Equally, where it is decided that such formalisation is too high a price to pay for the expected use – especially where that use is primarily human reading – the conceptual mapping information can be left in plain text format, attached as needed to relevant units. 

Common concepts and structures for all NOSs

At this point, having considered the structures actually occurring in the studied NOSs, the next task is to establish a set of concepts and structures which will be used in the projects to fit the NOS material. This will pave the way for deciding on a means of representing the information interoperably. 

A significant decision is about the extent to which the information should be idealised –  should problem cases be ignored? It seems best, at this stage, to try as far as possible to represent the NOS information “warts and all”, because idealisation is more likely to lead to stakeholders complaining that “their” way of seeing things is not accommodated in the common structures.

It seems then proper to base a set of common concepts around the features, already identified above, which are common to all the NOS information. To be acceptable, it would make sense to check that this relates to the most basic definitions of what NOSs are supposed to be. This was not taken up earlier in this report, because the priority was to examine what was actually contained in the NOSs, rather than to look at definitions of what they were supposed to contain. Now, on the other hand, it makes more sense to do this comparison. 

Definitions of NOSs

These were taken from the list returned by Google on searching for “National Occupational Standards”, as higher-ranking pages on Google are more likely to be more significant than lower-ranking pages. Three general definitions are readily available. 

According to the QCA, “National occupational standards are statements of the skills, knowledge and understanding needed in employment and clearly define the outcomes of competent performance.”

According to the Occupational Standards Directory, “National Occupational Standards (NOS) define the competences which apply to job roles or occupations in the form of statements of performance, knowledge and the evidence required to confirm competence.”

According to the Management Standards Consultancy, “National Occupational Standards (NOS) specify the standards of performance that people are expected to achieve in their work, and the knowledge and skills they need to perform effectively.”

These definitions confirm the view derived from analysis of the materials, that the key concepts and structures are the performance and knowledge statements themselves, and the jobs, roles or occupations for which they define competence. 

The statement items

On the surface, one might take it that there are just two kinds of statement item, one for performance and one for knowledge. However, the analysis of NOS materials has shown the need for caution here. There are some knowledge items which are phrased in a similar way to performance items, and many other knowledge items that are either grouped into separate categories of required knowledge and required awareness, or qualified by the phrases “working knowledge”, “in-depth understanding” etc. In effect, this means that there may not be agreement on the number of significantly different kinds of statement. The safest and most inclusive way to proceed is therefore to have just one fundamental concept of a NOS statement item, and leave room for different kinds of statement items to be distinguished for different purposes. 

It has been illustrated above that the words of individual statement items on their own, out of context, can be interpreted in different ways. But for a NOS to be useful, there has to be a large measure of general agreement or consensus about the meaning of each individual statement item. (If this were not the case, one authority could certify a candidate as competent for a particular item, where another would not accept that competence, and the whole system would fall apart.) Therefore, it seems prudent to include, in the fundamental concept of the statement item, sufficient contextual information for the item's intended meaning to be clear and unambiguous. 

For a statement item to be unambiguous and most widely meaningful, it needs to be associated with: 

It would appear that the identity of the statement item's element, within its unit, is not vital to the disambiguation of items, but is rather a classification accessory, to help group the statement items into meaningful sets. If this is true, the same statement should not appear in two elements of the same unit. (This has not been fully checked.) This grouping function is also sometimes done by intermediate sub-headings in a list of items.

When statement items belong to a unit constructed for the purpose of assessment for a specific level of qualification, an item may contain a list with a range. “Work with three of the following types of client...”. This contains conceptual mapping information that could be extracted and reused in other items. This will be discussed below under the heading of conceptual map. 

The unit

As previously discussed, units are defined by SSCs or other standards setting bodies, and do not all have the same structure. They do all have some kind of text – an introduction, summary, description, or similar material, however it may be titled. Text associated with the unit may appear under a number of headings. For the purposes of this study, there would not appear to be significant benefit in distinguishing different textual descriptive items from one another, particularly as there are no such distinctions present in many units. The common factors that can always be found are then these. 

  1. Which SSC or other body is responsible for the unit. This is implicit in the documentation, but if units are to appear out of context, this needs to be made clear. 
  2. A code (unique within that body's NOS material) and title. 
  3. Descriptive, explanatory, summary material. conceptual mapping information may be extractable from some of this material, like the keywords and definitions, and the scope. 
  4. A set of statement items that are covered by the unit, either directly, or indirectly through contained elements. 

There are also meaningful optional elements. 

  1. A single “home” set of NOS units (or “suite”) where the unit belongs most naturally (this is not present with some general units that belong equally to several sets) 
  2. Any elements into which the unit happens to be subdivided. 
  3. One or more locations in any relevant assessment or skills framework. 

Units also need to be identified in order that the statements contained in a unit can refer to that unit as their context. When the unit is presented in its (current) documentary form, each statement has its place in the document, from which it is clear which unit the statement belongs to, and any subdivisions of the unit under which the statement appears. But in an electronic context, where the information is not necessarily bound together in the same way, this cannot be assumed, and the information has to be provided explicitly. 

Unit titles are normally carefully chosen, and many of them seem unambiguous and not to require context for their interpretation. However, this is by no means universal. For example, unit AC21 of Skillset (shared with LANTRA) has the title “Contribute to the fulfilment of the audio visual production requirements”. Contribute what, one may well ask. There could conceivably be other units with the same name. The required disambiguating context is here provided by the NOS title: “Animal training in the audio visual industries”. However, not all units have a single parent NOS. In the Skillset materials, the F and X numbered units are common to several different NOSs, and do not have a unique NOS to refer to. They do, however, belong to the Skillset NOS set as a whole.

The common-sense approach appears to prevail in all NOS materials, that within the NOS materials of a particular body, each unit has a unique code. But codes are not guaranteed universally unique: there is nothing stopping different bodies using the same code to refer to different units. 

Thus, to identify a unit unambiguously requires at least the identity of the body which manages it, and the Unit code. The unit title is not necessary, but would help human recognition. 

Other concepts and structures

List of items. A list of items contains either items, or other lists of items, and may have a heading. The items may be in a defined order in the list, which may help presentation or understanding. This list should be noted as belonging to another list, an element or a unit, so that in effect it provides ordering and possible structure to an otherwise unordered list of items.

Element. An element also contains items or lists of items, but in addition it must have a title and a code. Within the Skillset materials, the element code is formed as a decimal extension of the unit code.

Set of units. In general, any set of units could be put together with a title and optionally some explanatory text. This is routinely done in all NOS documentation, and also through “suites” on the ukstandards site. The purpose may be simply to cover an occupational area – this is done in Skillset NOSs by including the set in a file. In Skills for Health this is done on the website, which is a more flexible arrangement, doing away with duplication of units. In such simple sets of units, the units may be grouped together under subheadings.

One particular purpose for sets of units is to define the requirements for a qualification at a given level. A collection for this purpose will need to specify which units are mandatory, which optional, and other conditions such as how many optional units must be taken. There may also be restrictions on allowed combinations of units. 

Range. As this is not explicitly described in the NOSs, to represent range requires a structure which does not map directly onto the current documentation. If the representation of domain concepts is rich enough (see conceptual map, following) then concepts where the range of applicability varies can be given an explicit set of possible values. Any statement that bounds the scope of applicability of a concept can then draw from those same values.

Conceptual map

What domain concepts can be extracted, represented and used in defining standards in an occupational domain? Doing this within a domain is challenging enough, but at least there are  some examples of conceptual maps to act as reference points. In contrast, it is even more of a challenge to attempt to provide a structure for, or an approach to, doing this across many domains.

Starting from the other end, what conceptual mapping structures could be used, if they were available? 

Both approaches could be of great benefit in the construction or assembly of NOS materials. To have available a menu of domain concepts, together with their definitions; and to have all previously defined ranges to hand, would surely help people towards a consistency of documentation across different units and sets of units. Statements could be constructed in the context of concepts that have already been defined, and in particular, the scope of statements and units could be defined with reference to lists of types of entity without the risk of forgetting items on the lists, or using confusing or confusable synonyms. 

Advice on how to construct a conceptual map is clearly beyond the scope of this present work. But if a conceptual map were available, it could be used in other representations through the use of identifiers to refer to the concepts, ranges, and elements of those ranges.  


This document has explored the structure of NOSs in two domains, and highlighted the common concepts and structures which can be used to represent NOS material in a machine processable way. Statements and units are the two most fundamental structures. Units need to be referenced to the body responsible for them; statements need to be referenced to their “parent” unit. 

Other structures are seen as secondary, though they may be useful for several purposes. Sets of units are vital for defining qualifications, but such sets needs to contain rules specifying which units are mandatory, which optional, etc. Subdivisions of a unit may be helpful aids to human comprehension, but are unlikely to be essential. 

The following related document takes up the question of how practically to represent these concepts and structures so that they can be made available electronically, through the Internet, and used and reused in many ways. 


Please see the list of links relevant to my involvement the project

page maintained by and © Simon Grant, edition 2007-05-29