Introduction to Class AY/I Science and the natural sciences ** file aybintr.tex 12.9.98 1 Scope of the class and its place in BC2 1.2 The natural sciences study the phenomema of the natural world, using as their fundamental mode of enquiry what is generally known as the scientific method. Although philosophers of science dispute certain of its features, its essence is that close observation of the phenomena, combined with the use of induction and deduction, leads to the advancing of an hypothesis as a provisional explanation of what is observed. This hypothesis is then analyzed and tested objectively by a wide variety of procedures in which measurement of the data involved and controlled experiments, as far as these are possible, are major features. From consideration of the evidence thus established the hypothesis is accepted, modified or rejected. Hypotheses which are thus validated may then form the basis of further hypotheses, thus building up the vast corpus of what is called scientific knowledge. Those parts of it which have been validated beyond any reasonable doubt take on the status of scientific laws. But it is fundamental to the idea of scientific enquiry that if further evidence demands the modification or even abandonment of a theory, however immutable it may seem to be, so be it. In this sense, science is the most modest of the major fields of knowledge in the claims it makes for its product. 1.3 When the classification of the vast and endlessly multiplying body of scientific knowledge is considered, the principle of gradation, supported by and reinforcing the concept of integrative levels, has proved to be a powerful and effective instrument. It produces a major organization of the field whereby phenomena are grouped into particular sciences which can then be presented in a sequence in which each successive science builds on the preceding ones. Successive sciences then study phenomena at higher and higher levels of complexity, in the sense that they require for their explanation not only knowledge of preceding classes but also of new or emergent phenomena. Bliss called this ordering 'gradation in speciality'. Thus, energy and matter at its most fundamental level is the subject matter of physics. Organized into more complex forms, at the molecular level, it gives the subject of chemistry and this is therefore regarded as being more 'special' than physics in its scope. At more complex levels, molecular aggregations give celestial bodies and planetary systems (the subject of astronomy and the earth sciences) and these constitute environments for the development of yet more complex forms in living matter. 1.31 At this latter stage in the ordering of the field of knowledge, the emergence of complex forms of social organization and of vast systems of artefacts and mentefacts introduces situations in which the scientific method ceases to be the dominant mode of enquiry (although it by no means becomes an irrelevant one). In classificatory terms. it seems to be the case that the principles of gradation and integrative levels have their major significance in the natural sciences and are less effective as instruments of classification in other fields. Bliss acknowledged this in naming the rest of the classification (following the last of the natural sciences, biology) the social sciences and human studies. 1.32 The situation indicated above is reflected in current discussions of the limits of the scientific method. Gradation (and to a lesser degree integrative levels) reflects a reductionist view and has been categorized somewhat disparagingly as "nothing but-ism" - ie mind (the most complex element in the last of the sciences, biology) is treated as nothing more than a machine - a computer made of meat, as Marvin Minsky put it. Many contributors to the debate (including many eminent scientists) are critical of this "materialist monism" as it has been called. The recognition of the intercovertibility of energy and matter which heralded the beginning of this century is now invoked to suggest that a further reconciliation of mind and matter is required to account for a number of phenomena in which mind has been demonstrated to affect matter in a significant manner; examples of this are the placebo effect and the ability of deep hypnosis to affect biochemical processes in the body. That such phenomena are dismissed by many as unscientific is not necessarily a fatal criticism when we remember the essential nature of the scientific method mentioned in section 1.2 above. 1.33 Although the debate as to the limits of scientific causation may raise questions as to its scope (questions which are obviously relevant to a general classification of all knowledge) it should be remembered that a principle like gradation has been used in BC2 not as an assertion of a particular interpretation of the nature of the sciences but as an instrument of proven value in the organization of knowledge. It contributes significantly to an organization which is readily communicable, operates with exceptional consistency, and facilitates the locating and relating of classes of knowledgge with a high degree of predictability - a major virtue in an instrument for information retrieval. 1.4 In the metascientific fields of knowlege which Bliss characterized as the human studies, the subject of technology (covering most of the physical artefacts of humanity) has a particularly close relationship to science. This is reflected in the fact that the general science class (AY2/AYY) is preceded (at AY1) by an even broader class, science and technology in general. The appearance of this class at AY1 is entirely a reflection of literary warrant and not of the principles of gradation or integrative levels. There is a symbiotic relationship between science and technology. It is well know that many significant developments in science have waited on the invention of artefacts to assist the process of scientific enquiry. Major examples are the dependence of optics on the development of effective optical instruments and, in turn, the dependence of other sciences on these (of biology on the microscope, of astronomy on the telescope and so on). The reverse process, in which scientific discoveries prove the basis for the development of new technologies, is equally well known and has been particularly conspicuous in the past two centuries. 1.41 This close relationship does not mean that technology should be regarded as applied science. Much of it is not particularly 'scientific' and its objectives are quite different. The cental objective of science is to elucidate the nature of phenomena dispassionately and objectively. The purpose of technology is to serve the material interests of humans. The principle of gradation implies not only that a clear distiction be drawn between technology and science but that the latter, as a product of human social activity, should file after those studies which have the structure of society and its major social processes as their subject 1.42 Nevertheless, having acknowledged these differences, the fact remains that some of the products of technology play an important and even crucial role in science. It is not merely that scientific instruments (a major part of the Agents facet in general science) are primarily the product of technology. There is also the fact that some of them raise acutely the distinction between natural phenomena (the legitimate object of scientific enquiry, demanding a location within science itself) and applications of these (which are not). Whilst some artificial products are readily accepted as quasi-natural phenomena (eg the transuranic elements, which are artificial radionuclides, produced by bombarding heavy atoms with high-energy particles) this is partly because their production is primarily an element in the scientific study of the closely related natural phenomena. But many occasions now arise where natural phenomena are subjected to highly sophisticated and contrived manipulations designed primarily to serve utilitarian human purposes; an obvious example concerns the application of optical phenomena associated with holography. Whether such concepts should be regarded as part of physics or of physics-based technology poses a problem in the classification of science and technology. This problem is considered further in the introduction to Class B Physics (section 10). 1.43 The conclusion reached by Bliss after considering such problems was that technology should be a separate class, following the social sciences and collocated with economics, the social science concerned with the production and distribution of society's material wealth. However, Bliss provided alternative locations whereby a library could collocate a technology with its dominant scientific base in cases where a close relationship held. BC2 continues this policy but with an important modification. In the case of biological technology, the study of the science and its possible applications is so intimately connected that a complete separation would be both extremely difficult and unlhelpful. This is particularly true of medicine; here, problems of human biology which are indisputably 'natural' phenomena and the legitimate province of the science are nevertheless studied primarily because of the utility that knowledge of them would have for human welfare. A classification of medicine which did not embrace human biology woulr be a very defective one. So the biology classes in BC2 (E/I) include substantial portions of applied science - ie technology. 2 Structure of Class AY/I 2.1 All classes in BC2 are designed consistently according to a basic pattern which reflects the six fundamental features of a modern documentary classification. In the design operation, these six features are taken (analogously to the principle of gradation) in an invariant order in which each step depends on the proeceding ones, but not vice-versa. The steps are, in order: 2.11 Organizing the terms into broad facets; 2.12 Organizing the terms in each facet into specific arrays (sub-facets); 2.13 Deciding the citation order between the facets and between the arrays; 2.14 Deciding the filing order of the facets and of the arrays within them; 2.15 Adding a notation, in which every class is represented by a symbol possessing ordinal value, to faciitate locating the class in the file; 2.16 Adding an alphabetical index, whereby a use can go directly from the name of a class to its position in the notation and file. 2.2 The theory underlying these feature is explained in detail in the Introduction to BC2 (Ref.3). Here, the structure of Class AY/I is described in the same order of fundamental features and it is assumed that users of this class will familiarize themselves with the essentials of the theory explained in the Introduction. 3 Facet structure of Class AY/I Science and the natural sciences 3.1 The main feature of the schedule is a strict adherence to the principles of facet analysis. A facet consists of the sum of classes produced when the vocabulary of a subject is divided by one broad principle of division. So the terms making up the vocabulary of science are initially organized into ('divided into') broad facets, so that terms representing concepts which all stand in the same broad relationship to the containing class are found in the same facet. For example, all terms reflecting the notion of a natural phenomenon investigated in science (eg energy, matter, molecule, star, planet, atmosphere, river, plant, animal) are brought together in an Objects of scientific enquiry facet. All terms reflecting a subsystem of any of the above (eg the lithosphere, hydrosphere and atmosphere of a planet, the regional parts or organs of an organism) are brought together in a Subsystems (Parts) facet - and so on. 3.2 Facets in Class AY/I The facets identified are summarized below; their scope and relations are considered in more detail under citation order (section 4.5). 3.21 The entities and systems defining the objects of scientific enquiry; eg energy and matter, molecular systems, stars, planets, living things. 3.22 Subsystems and parts of the entities; eg lithosphere, nervous system. 3.23 Properties and processes of entities and subsystems; eg distribution, dimension, deformation, diastrophism, respiration, reproduction. 3.24 Operations: actions performed on all the above by human agents - eg recording, measuring, visualizing, analyzing. Operation are distinct from processes, which are activities internal to a system, as in the examples in 3.23. 3.25 Agents of processes and of operations; eg catalysts, equipment, instruments, materials. 3.26 Common subdivision (CSD); concepts which are to be found in all subjects and which refer largely to the human study and practice of the subject and the conditions (eg of time and place) under which is or has been pursued. 3.3 Arrays within facets 3.31 Most facets contain terms which reflect different specific principles of division, whereas a facet as a whole reflects only one broad principle of division. For example, in biology, a major facet is that of Types of organisms; these may be further divided by specific principles like taxonomic status, habitat, sex, age and so on. 3.32 This operates at every level of the classification; eg as specific a concept as fluid flow (itself reflecting the intersection of an entity, the state of matter Fluid, and a process, Flow) may still be divided by a large number of different specific principles of division, giving such classes as conical flow, compressible flow, viscous flow, laminar flow, etc. 3.33 Terms in an array are mutually exclusive, so there is no question of compoundsing between them; eg there is no class of turbulent laminar flow. So the crucial problem of citation order between the components of a compound (see section 7) no longer arises within an array - only between them (eg to give a compound like viscous laminar flow). 4 Citation order (combination order) 4.1 This refers to the order in which the elements of a compound class (one consisting of more than one element, whether from different facets or from different arrays) are combined (cited) in a heading; eg whether the heading (which reflects the order in which the classes and subclasses are taken) is Animals - Birds - Aquatic - Charadriiformes - Behaviour or Animals - Birds - Behaviour - Aquatic - Charadriiformes or Animals - Behaviour - Birds - Aquatic - Charadriiformes or any of the other 23 permutations possible here. 4.2 Citation order reflects the order of application of principles of division and determines which concepts are subordinated to which; eg using the first heading above would scatter literature on animal behaviour according to the number of types of animals. 4.3 If a consistent citation order is followed, the scattering of some subjects because of their subordination to another (an inevitable feature of classification applied to a linear order, whether of documents on library shelves or entries in manual catalogues) is strictly controlled and the location of quite complex classes (reflecting the compounding of several different facets or arrays) is always predictable. The retrieval of the information on the scattered classes is thus ensured. 4.4 Citation order is the most important feature of a classification system. But clear and consistent rules for it can only be expressed in terms of the facets and arrays involved - hence the prior need to organize terms into their facets and arrays (see the order of operational steps in section 2.1). 4.5 Citation order between facets In all its classes, BC2 seeks to observe as far as possible the 'standard' citation order. In any subject, this takes as the primary facet (the first-cited one) that facet which reflects the ultimate purpose or object of study in the subject, and within which the other concepts and their facets are defined. Each class in the facet may then be divided into the following facets and in the following order: Types, Parts, Properties, Processes, Operations (actions on it), Agents (of processes and operations), Common subdivisions The following notes explain how these general rules have been applied to Class AY/I. 4.51 The primary facet consists of the entities defining the objects of scientific enquiry. They embrace fundamental manifestations of energy and matter (kinetic energy, forms of motion, waves, electromagnetism, particles and more complex aggregations of thes (molecular, astronomical and planetary, living organisms). The concepts making up these classes are easily recognized as defining the well-known sub-disciplines of science (physics, chemistry, etc). 4.52 The second-cited facet consists of the Subsystems and Parts of these; this facet has no general class independently of the entities above, only those subsystems special to a given entity and which vary widely according to the entity. It includes subsystems of chemical molecular systems, parts of planets such as lithospheres and atmospheres, the regional parts and organs of living things. 4.53 The third-cited facet consists of Properties and Processes of systems and subsystems. These range from ubiquitous concepts appearing in all systems (eg distribution, variation, frequency, dimension) to specialized ones such as oxidation and reduction in chemical substances, tectonic and degrading processes in planets, and respiration, evolution, etc. in living things. 4.531 Properties are conceptually distinct from processes (actions internal to a system); eg colour is a property, change is a process. 4.532 Where the distinction is clear, two different facets will be recognized; but in many fields the distinction is so blurred that the two facets are conflated. In terms of citation order, property is always subordinated to whatever it qualifies, whether this is an entity, a process or even another property (eg the durability of a colour). 4.54 The fourth-cited facet consists of Operations; these are actions performed on all the above by human operators and their agents, as distinguished from processes, which are activities internala to a system, such as the physiology of living things. 4.55 The fifth-cited facet consists of Agents; these are usually agents of Operations, such as equipment and instrumentation. But the relationship of action/agent also occurs with processes (eg enzymes acting as biochemical agents in a physiological process). 4.56 The sixth-cited facet consists of Common Subivisions (CSD); these are concepts which are to be found in all subjects and provided for in BC2 by Common Auxiliary Schedule 1, applicable to all classes. They range from bibliographical forms (dictionaries, graphic materials, etc) to operations like study and research and agents of these such as organizations.They also include the two major facets of Time and Space in their commonly occurring manifestations of chronological periods and geographic places. The concepts of Time and Space as fundamental parameters in natural phenomena are regarded as subject classes in physics (at B9B). 4.6 Citation order within facets (between arrays) 4.61 There are no general principles as yet available for deciding citation order between arrays. Decisions are largely empirical, based on considerations of whether any given compound (reflecting two or more different arrays) would most helpfully go. 4.62 The number of different arrays is often so large that it is out of the question to list them in citation order as is done for facets in section 5. However, the order in which they should be cited is shown clearly by the inverted filing order (see section 5.2 below); an array filing later (further down) in the schedule should be cited before one filing earlier (see examples in section 5.24 below). 4.7 General indexing rules for citation order 4.71 The rules described above govern by far the greater number of decisions for compounding in BC2. However, a number of well-established indexing rules, all of them consistent with the standar citation order, are also observed and are very useful in practical classification (see Introduction to BC2 (Ref. 3) section 7.331). Sometimes, these demand that synthesis should be by building forward, not retroactively. This is because the normal relationship between the facets or arrays has changed. The most prominent of these is probably the rule for citing in the order Patient (ie recipient of action) - Action - Agent. This is usually taken care of by the normal citation order; eg Techniques in scientific investigation AY6/AY7 file after Equipment and Materials AY3/AY5 and are cited before them. But when one thing influences another (a special case of the agent relationship) the influencing factor, which is cited second, may file after the thing affected; eg thermoacoustics BRG_HGP is built by citing acoustics (BRG_H) before thermal properties (BRG_P) although acoustics (here, the thing affected) files before thermal proerties. 4.72 The situation may be generalized thus: whenever the relationship between concepts varies from that embodied in the standard citation order, these general indexing rules should be invoked. 5 Filing order 5.1 This is the order in which the individual classes, simple or compound, file one after the other, whether in the schedule, on the shelves or in a catalogue or bibliography. It has two quite separate components - facet filing order and order in array. 5.2 Facet filing order 5.21 This is the order in which the different facets, each one containing a block of different classes, file one after the other. 5.22 All schedules in BC2 are inverted ones; ie the facets file in an order which is the reverse of the order in which they are cited when compounding terms to form compoun classes. So the primary facet files last, the second-cited facet files next to last, and so on. 5.23 The reason for this (see the Introduction to BC2 (Ref.3) is solely to preserve a consistent order of general-before-special. The assumption that a general class should file before its subclasses is virtually universal. 5.24 Example of an inverted schedule: G Zoology, animals (Processes) GHT Behaviour (Types of animals) (Types by development) GL Young (Types by habitat) GN Aquatic (Types by taxonomy) GP Birds GPH_T Behaviour GPN Aquatic birds GPP_T Eagles GPP_THT Behaviour 5.25 In the file above, the compund Bird behaviour (GPH_T) files after both the more general classes to which it belongs (Animal behaviour GHT and Birds GP). If the schedule were not inverted, and the Processes facet filed after the Types of animals facet (just as it is cited after it) the general class Animal behaviour would file after its subclass Bird behaviour. 5.26 Similarly, within each each facet the arrays are inverted - the first- cited array files last, the second-cited array files next to last, and so on. 5.27 It was noted in section 4.1 that the inverted filing order embodies within itself a comprehensive guide to the citation order. The sequence of classes in 5.24 demonstrates this. It implies, inter alia, that a process is cited after a type of animal; also, that within the Types facet an animal characterized by its taxonomic class is cited before its habitat. 5.3 Order in array 5.31 The classes in an array are mutually exclusive and cannot normally be compounded (see section 3.33). So their filing order cannot be determined by citation determined by citation order. Where there is an obviously helpful order, that is used; eg chronological order of periods in AY7 History of science; evolutionary order, reflecting development over time, of organisms in biology; geographical order of places in DU Geography. 5.32 However, order in array is usually pragmatic. The filing order of the individual sciences is a somewhat special case and is probably best regarded as that of a quasi-facet order. The order is essentially on of gradation and integrative levels and provides both a filing order and a citation order. Compounding between the special sciences (which is not uncommon) conforms to the basic retroactive rule, the class filing later being cited before that filing earlier; so the physics of chemical substances, of astronomical bodies, of terrestrial processes, of biological processes, etc all go under the class filing later, not under physics. 6 Alternative treatments and arrangements in the order of classes 6.1 These serve the demands of particular types of libraries. In each case, the notation has been designed specifically to allow alterations to be made to the preferred arrangement. In all cases, the preferred arrangement is stated clearly and any special notational instructions needed to implement the alternative are indented under the note for it. The general pros and cons of alternatives are explained in the Introduction to BC2 (Ref.3). 6.2 The main alternatives in Class AY/I are noted in the separate introductions to the classes concerned. One common to all the sciences is that for the collocation with its science of the applied science or technology of that science. But note that in the case of the biological sciences, the collocation of the technology with biology is the preferred arrangement. 7 Notation This is explained in detail in the Introduction to BC2 (Ref.3), Only its main features are described here. 7.1 Notation is a system of classmarks representing the terms (classes) of a classification. Its function is to locate in a mechanical fashion the position of each and every class, simple or compound, in the system. It does this mechanically because the symbols (in BC2, capital letters and numerals) have an ordinal (positional) value already well known to the users. The only special ordinal value the user of BC2 must remember is that a number files before a letter; eg AY9 files before AYA. 7.2 The notation is purely ordinal - ie it makes no attempt to express hierarchical relations by adding another character to symbolize each step of division. Such an attempt must always fail sooner or later and more likely sooner. So BC2 notation concentrates on the primary function of notation, which is simply to maintain the order of classes already determined completely by the theoretical rules governing order (citation order and filing order). By doing this, it secures classmarks which are as brief and as simple as possible. For example: AY3_6 Practical scientific work AY3_B Equipment & materials AY3_U Equipment & plant AY4 Scientific instruments AY4_5 Components AY4_K Switching devices 7.3 Only one classmark in the above chain (sequence of successively subordinate classes) is 'hierarchical' in that it adds a character to the classmark of its immediate containing class; ie AY4_5 can be 'seen' to be subordinate to AY4. On the other hand, the classmarks are much shorter than they would have been otherwise; eg the last class would need a classmark nine characters long if the notation were hierarchical. 7.4 It should be emphasized that notation in no way determines the order of the classification. The order is determined entirely by the theoretical principles and rules described in sections 3/6 above. All that notation does is to maintain this order mechanically; it is the servant of the order, not the master. Nevertheless, notation is an important feature of a classification; as Bliss said, it may not make the classification, but it may mar it. BC2 seeks to keep notation as brief as possible (whilst still being as specific as possible in pin- pointing classes) since brevity is the major element in simplicity. 7.5 The notation is fully faceted and synthetic. Compound classes formed by the intersection (coordination) of two or more separate concepts or classes are given classmarks which are built ('synthesized') from the simpler constituent classes according to strict rules. These are explained fully in the Introduction to BC2 (Ref.3) but the essential ones are repeated here for convenience. 7.51 The main function of synthesis in notation is to provide maximum hospitality. Within any subject, the number of potential classes is enormous. Every term in every facet is theoretically capable of intersecting with every term in every other facet. Although the literature may reflect a large number of these, this number is still only a fraction of the number it might conceivably deal with. The notation must be flexible enough to accommodate all of them. 7.511 It must also, of course, be able to accommodate new concepts as they arise. It is assumed that new concepts will always fit into existing facets, which reflect categories of concepts fundamental enough to ensure this. The provision of correctly located classmarks for newly inserted concepts is also facilitated by the ordinal notation, which suffers far less from rigidity (as Ranganathan called it) than so-called hierarchical notation. 7.52 Enumeration of compound classes in the schedule 7.521 Because of the practical impossibility of printing out ('enumerating') in the schedules all the compound classes which may arise, a faceted classification may decide to adopt a rigorous policy of not giving any. This was the case in the first fully faceted classification to be made - the Colon classification of S.R Ranganathan. This simply listed all the elementary terms in their facets and left it to the classifier to build the classmarks for all compound classes as they appeared in the documents being classified. 7.522 For a number of reasons this schedule style is not followed in BC2, which enumerates a fair number of compound classes. The main reason is that this assists the classifier to grasp the structure of the whole class as it affects the particular class concerned. It shows clearly how the the concepts in a subject are handled consistently despite the ambiguities and confusions in the terminology. These are far more prevalent in the case of the natural sciences than is warranted by the description of their terminology as being 'hard' (as compared to the 'soft' terminology of the social sciences). Wherever necessary, definitions of terms are given so that the classifier can see why the concept has been classified as it has been. Enumeration of compound classes also facilitates the provision of A/Z index entries for important compound classes (which would not get an entry were the schedules to be confined to the elementary terms). 7.523 In such cases (of some enumerated compound classes appearing in the schedule) it should not be thought that the detail under that part is limited to the subclasses thus enumerated. When assessing the specificity of the vocabulary in a given class it should always be remembered that the class may be qualified by all earlier facet and arrays, whether this is hinted at by a limited enumeration or not. For example, there is enumeration of the class Neutron-neutron interaction at BNW_QW; but this could easily be notated if the need arose. 7.6 Classmark building (synthesis) This is best demonstrated by detailed examples from a specific class; so the explanations in the introduction to Class B Physics may serve to demonstrate the problems for all the sciences. Here, only the briefest summary of the position is given. 7.61 The chief method of synthesis is by retroactive notation. It must be remembered that compounding in BC2 is nearly always done by qualifying a given class by one or more other classes preceding it in the schedules. The classmark for the compound is obtained by adding the earlier classmark directly to the later one after dropping any initial letters (or, much less commonly, numbers) common to the two classmarks being joined; eg BF Waves BM Particles BMF Particle waves Here, the earlier class (waves) is added directly to the later one (particles) after first dropping the initial B, which is common to both of them. 7.611 A distinction may be noted between retroactive synthesis and retroactive notation. The former refers to all forms of synthesis in an inverted file, when a classmark is built by going back in the schedule to get the further components in a compound class. Retroactive notation refers to the specific notational device of reserving or dedicating the initial letters of earlier classes before enumerating the subclasses special to a given class; eg the first special subclass of BM Particles doesn't appear until BMM since all the preceding divisions of B (BA/BL) have been reserved to allow their direct addition as qualifiers of BM (as in BMF) without clashing with the subclasses special to BM. 7.612 Another distinction worth noting is that of a notational facet, as distinct from the more commonly referred to conceptual facet. A notational facet is the set of subclasses beginning with the same initial notation; eg the notational facet AY7 consists of all the subclasses beginning with AY7 (whereas the conceptual facet of Techniques in scientific investigation in which it appears covers AY6/AY7). This distinction is useful when considering how many letters can be dropped in retroactive notation. 7.62 The second method of synthesis uses an intercalator. This is any letter or number used to introduce subclasses other than by the automatic operation of retroactive notation. It is always accompanied by an Add instruction; eg AY3_B Equipment & materials (in scientific investigations) AY3_K (Physical properties of equipment & materials) * Add to AY3_K letters A/W following B; eg AY3_KGP Thermal properties [from BGP] 7.621 An important use of intercalators is when every member of a large class has to be qualified by a standard set of subclasses (eg every particle in physics, any given element in chemistry). 7.622 Intercalators are quite prominent in Class B Physics and the Introduction to Class B Physics (section 8.4) givesa further examples. 7.7 The different ways of building classmarks described above may give an impression of complexity at first reading. But so would the simplest action if described in terms of its basic operational steps. The detailed sequence of instruction we need to give a computer before it can process the simplest operation demonstrates this. Applying notation is a practical operation; the steps involved are basically simple and quickly become familiar after a little practice. 8 The alphabetical subject index The function of the A/Z index to a classified indexing system is considered in the Introduction to BC2 (Ref.3) (section 6.5 gives general principles and section 7.5 gives practical guidance for a library making its own A/Z index to its own stock). Only the basic features are given here. 8.1 The main points to be remembered for the efficient use of the printed index to the schedules in this volume are given on the page preceding the A/Z index. 8.2 The A/Z index to this volume is essentially a quick guide to the location of any given concept in the schedules. It is important to remember that it is not a substitute for the categorized and hierarchical display of the schedules. The classifier should never classify solely by the index, but turn to the schedules to verify that a given context is the correct one for the concept as used. 8.3 Most of the terms indexed are elementary ones, whereas much of the literature to be classified reflects several such terms combined in some form. The classifier must be thoroughly familiar with the basic rules governing how these terms are put together in order to get a classmark which locates the compound accurately in its correct context. 8.4 The basic rules followed in making the index are those of chain indexing. This is a highly economical way of reducing the number of entries needed for compound classes whilst ensuring that all keywords likely to be sought by a user of the index will still appear. The main rule is very simple: if a term is qualified at all, it is by a superordinate term (ie its containing class, which helps to define it). An entry term is never qualified (followed by) a term representing one of its own subclasses in the schedule; eg entries may appear for Propagation of waves BFC Waves BF but NOT for Waves, Propagation BFC since the last class represents a subclass of waves in the schedule. Should a user of the index consult it under the last form, and not find it, they will nevertheless find the direction to BF Waves (in general) and can locate the desired subclass in a slightly less direct way via the schedule. 8.5 The A/Z index to BC2 classes is now produced largely by automatic selection of terms from the schedules, using a computer program written to this end. This include, for example, rules for deleting 'anti-chain' entries; this ensures that no entry appears for Wave propagation (say). 8.6 A problem which will need resolving when BC2 is complete is that of a consolidated A/Z index. The obvious desirability of one A/Z index to all the sciences and not just to AY and B anticipates the more general problem. The Bliss Classification Association has begun looking at this, but until BC2 is complete the actual production of such an index is, unfortunately, not practicable. 9 Practical classification in AY/I Guidance on this , with demonstrations of the different siuations which arise, will be found in the Introduction to Class B Physics. 10 Applications of Class AY/I 10.1 The use of BC2 to arrange files of documents or catalogue entries for them, including the provision of a conceptual framework to assist the analysis of the documents, should be clear from the various sections above. But BC2 is also extremely useful in the construction and searching of automated as well as manual databases. 10.2 Automated databases and catalogues 10.21 Reference has already been made in the Introduction to Volume AY/B (section 2.2) to Jean Aitchison's paper in the Journal of Documentation on the use of BC2 in this context. An even more detailed account, albeit one restricted to a single subject field for its examples, is given in the introduction to Chris Preddle's revised edition of Class Q Social welfare and criminology (Bowker-Saur, 1996). It considers the problems of subject keyword indexing, the precoordination of terms, indexing aids in controlling preferred terms, synonyms, etc, subject keyword searching, thesaurus construction and searching for documents by searching classmarks. 10.22 Ideally, the substance of the above would be repeated here, but using the vocabulary of science for its demonstrations. However, the exigencies of getting this first volume of the BC2 classification of the sciences published without further delay have made this impracticable. But although the examples used in the Class Q Introduction are drawn from a quite different field of knowledge, the principles involved are much the same as will be found in any field and their exposition should proved of great help to users of this volume until an exposition tailor-made to the needs of the sciences is available. 10.3 The use of BC2 in constructing traditional manual catalogues is considered in the Introduction to BC2 (Ref.3) and will not be repeated here. Excellent comments on this problem will also be found in the Introduction to Class Q. 11 General science and physics in BC2 compared with BC1 11.1 The general sequence of the sciences in BC2 is virtually the same as in BC1. This is not surprising, since the main-class order has always been recognized as the greatest strength of BC1. But within each individual science, the differences between BC1 and BC2 are very substantial indeed, both as to the organization of classes and the size of vocabulary. These differences in the individual sciences are considered under each science and only AY and B are considered here. 11.2 Class AY In BC1 the subject of science in general is at AK, following philosophy (A/AJ) and preceding logic (AL). Bliss acknowledged that both logic and mathematics (AM/AY in BC1) were not sciences properly, being concerned not with the observation of natural phenomena per se but with general methods applicable to all subjects, and particularly to philosophy and science. Nevertheless, he described them as abstract sciences which made a bridge between philosophy and science proper. BC2 has interpreted the scope of the latter as it is more generally understood, as consisting of the empirical sciences concerned with 'objective realities' as Bliss put it. By this reckoning they are more concrete than logic and mathematics and therefore follow them in main-class order. 11.3 The small vocabulary of AK in BC1 consists mainly of relatively generalized terms which tend to mix up concepts usually regarded as beloging to the common subdivisions (eg surveys, recreations in science), social relationships of science (eg science and theology, science impostors, applications to industry) and scientific operations (eg organization of research). Only one classmark is given to the agents of scientific activity (laboratories and equipment) and this is separated from scientific instruments, which is preferred under physical sciences (AZN). There is only one concept representing the general processes and properties (AKS Symmetry and conformity in natural objects). Although AK contains several concepts relating to different categories of sciences (eg exact sciences, formal sciences, natural sciences, sciences grouped for some purpose) the general concept is not completed until the widely separated class for physical sciences at AZ. 11.4 The overall order of Class B Physics in BC1 is broadly similar to that in BC2, but lacks consistency in its categorization. This is best shown by outlining it: BA/BB Theoretical & practical physics BC/BD Mechanics BE/BF Matter & energy... Radiation BG Properties of matter, changes of state BH/BL Heat... Light... Electricity & magnetism... BM/BO Electrical techology & Engineering BP Sound BQ/BR Hydromechanics & hydraulic engineering BS/BT Aerodynamics & aeronautics BU Physical technology 11.41 In terms of facet structure this shows some confusion. Although BG, for example, includes the general classes for the particular states of matter (which are given in the same order as in BC2 - Fluids... Gases... Liquids... Solids) the content of these classes is scattered (at BQ/BT) with little apparent rationale. No clear distinction is made between the particular states of matter and the processes concerned in their changes. 11.42 The general state of this internal structure in the class is one reflecting the state of library classification before Ranganathan introduced the strict application of the rules of logical division in sorting out categories of concepts and developing clear rules for their interaction. 11.5 The other striking difference between BC1 and BC2 in the two classes is the size of vocabulary. It is very difficult to give even an approximate figure for the size of vocabulary in a synthetic classification, since the compounding of classes can generate tens of thousands of classes if the literature demands it. 11.51 If we consider only those terms enumerated in the schedules with a specific classmark, BC2 has something like twenty times as many terms as BC1 in the general science class and some twelve times as many in physics. The figures (very roughly indeed) are: for general science BC1 has (in AK and AY) some 50 enumerated classes of which some 40 have individual classmarks. BC2 has (in AY) some 1100 enumerated classes. These figures exclude the Common subdivisions, or the disparity would be even greater. In physics, BC1 has some 600 enumerated classes, of which only about half have an individual classmark; BC2 has between 3500 and 4000 enumerated terms, all with individual classmarks. 11.52 When it is remembered that BC2 is a fully synthetic scheme, whereas BC1 has very limited synthesis in its two classes, these differences in range of vocabulary increase more or less beyond measure.