The TEI Header was defined in the first phase of the project, largely within the TEI working committee on Text Documentation, whose members included professional librarians and archivists as well as experts in markup. It was subsequently revised and expanded, with significant input from several TEI Working Groups, notably those concerned with the encoding of spoken language, and on the organization of language corpora. Its primary object is to address the problems of describing an encoded work so that the text itself, its source, its encoding, and its revisions are all thoroughly documented. Such documentation is equally necessary for scholars using the texts, for software processing them, and for cataloguers in libraries and archives. Together these descriptions and declarations provide an electronic analogue to the title page attached to a printed work. They also constitute an equivalent for the content of the code books or introductory manuals customarily accompanying electronic data sets. (TEI P3, p. 89). It is noteworthy that this electronic titlepage is almost the only feature of the TEI encoding scheme which is mandatory.

It consists of the following four major sections: a file description, tagged fileDesc, containing a full bibliographical description of the computer file itself, from which a user of the text could derive a proper bibliographic citation, or which a librarian or archivist could use in creating a catalogue entry recording its presence within a library or archive. The file description also includes information about the source or sources from which the electronic text was derived. an encoding description, tagged encodingDesc, which describes the relationship between an electronic text and its source or sources. It allows for detailed description of whether (or how) the text was normalized during transcription, how the encoder resolved ambiguities in the source, what levels of encoding or analysis were applied, and similar matters. a text profile, tagged profileDesc, containing classificatory and contextual information about the text, such as its subject matter, the situation in which it was produced, the individuals described by or participating in producing it, and so forth. a revision history, tagged revisionDesc, which allows the encoder to provide a history of changes made during the development of the electronic text.

The structure of a TEI Header is fully detailed in the and contains specific elements for a very wide range of elements (notably, almost all of those identified in the Survey of Libraries' Metadata Requirements reported in, section 7). It should be stressed that this structure is architectural, rather than legislative: in other words, the TEI proposes a rich collection of metadata components, and a structure within which they can be expressed, and expanded. It provides little or no guidance as to the particular selection of such components which should be used by particular projects. Definition of such TEI Applications was consciously left to users of the scheme by its designers. Consequently, headers defined by different projects may vary widely. However, there are increasing signs of convergence amongst (for example) the practice of the growing number of electronic text centres and archives employing the TEI Header to document their holdings.

The following header is from the Victorian Women Writers Project at Indiana University: Bevington, Louisa Sarah (Guggenberger) (1845-?) Transcribed and encoded by Felix Jung Edited by Perry Willett TEI formatted filesize uncompressed: 1426 bytes Library Electronic Text Resource Service (LETRS), Indiana University September 22, 1995

© 1995, The Trustees of Indiana University. Indiana University makes a claim of copyright only to original contributions made by the Victorian Women Writers Project participants and other members of the university community. Indiana University makes no claim of copyright to the original text. Permission is granted to download, transmit or otherwise reproduce, distribute or display the contributions to this work claimed by Indiana University for non-profit educational purposes, provided that this header is included in its entirety. For inquiries about commercial uses, please contact:

This example demonstrates how traditional cataloguing (bibliographical) information, rights and permissions information, specific encoding details, and version information are readily combined in one descriptive framework. The same encoding framework also applies to the text itself, of course, since this is also encoded according to the TEI Guidelines. A computer application capable of handling such a resource is ipso facto capable of handling its associated metadata.

A second example TEI header is taken from one of the 4124 texts making up the British National Corpus (British National Corpus, 1994). In this project some of the tags proposed by the TEI have been renamed, and the flexibility of the scheme greatly curtailed. However, the basic structure remains the same.

This example also demonstrates how the integration of the header and text within a single encoding framework can be beneficial. The catRef element in the header above specifies the descriptive (classificatory) categories applicable to the specific text to which it is attached, by reference only. A full definition for each category used in the corpus is supplied in an additional corpus header, which is prefixed to the whole corpus. Each individual text header references the parts of the corpus header which apply to it by means of TEI pointers, as in this case. This kind of linking mechanism is widely used within the TEI scheme, with obvious advantages of consistency and validation. As a further example, a language element can be given in the header to define each language used throughout a text. For a multilingual text, each portion in a given language will then reference the appropriate language element using its lang attribute. The lang attribute is applicable to any element in the TEI scheme, which makes it possible to indicate changes of language at any desired level of granularity, from sections or subsections down to individual words.

The TEI scheme also proposes a number of mechanisms for the embedding of metadata within the body of a text (as distinct from in the header prefixed to one). These mechanisms vary widely in their technical sophistication and expressive power, since they are intended to cater for a wide range of analytic needs. At the simplest end of the scale, an index element is provided, which can be placed anywhere within a TEI text to generate an index-entry of some kind for this point in the text (this is functionally equivalent to the CIMI topic element discussed below); for more complex interpretative structures, the interp element may be used both to define an analysis, and to link it to a span of text; interp elements can also be grouped into hierarchically organized interpGrp elements.

The TEI also defines a specialized tag set for the encoding of analytic interpretations of any kind, based on the feature structure formalism. This powerful mechanism has great potential for the representation of formal systems of all kinds, but has not yet been widely implemented. (See further Langendoen and Simons 1995)

The origins of the Encoded Archival Description (EAD) framework can be traced to a project initiated by the University of California, Berkeley, Library in 1993. The goal of the Berkeley project was to investigate the desirability and feasibility of developing a non-proprietary standard for machine-readable finding aids, that is, the inventories, registers, indexes, and other documents created by archives, libraries, museums, and manuscript repositories to support the use of their holdings. An additional motivation was the growing importance of networks as a means of gaining access to such information about holdings and the desire to extend the scope and richness of the information generally provided by traditional machine-readable cataloging (MARC) records.

The principles underlying the EAD are summarized as follows in an early definition of the project (Ann Arbor 1994) The information in a finding aid describes, controls, and provides access to other information, and thus is not an end in itself. Finding aids are not objects of study but rather tools leading to such objects. Although the encoding scheme does not define or prescribe intellectual content for finding aids, it does define content designation ... While there are certain elements that ought to appear in any finding aid, various intellectual and economic factors influence the depth and detail of analysis employed. Taking this into consideration, the encoding scheme is designed with a minimum of required elements, but allows for progressively more detailed and specific levels of description as desired. The standard preserves and enhances the current functionality of existing registers and inventories. The standard is intended to facilitate interchange and portability. It will increase the intelligibility of finding aids within and across institutions, permit the sharing of identical data in two or more finding aids, and assist in the creation of union databases. It will also ensure that machine-readable finding aids will endure changing hardware and software platforms because they will be based on a platform-independent standard. The needs of public users, curatorial and reference staff, and finding aid authors were given priority in the standard's design ... The designers sought to create a DTD that can be easily mastered and incorporated into routine finding aid production by staff possessing only a minimal knowledge of SGML.

These principles led to a design in which, at the most basic level, a finding aid document consists of two or three segments: a segment that provides information about the finding aid itself (its title, compiler, compilation date, etc.); an optional segment containing hand-generated front matter (title page, acknowledgements or preface for the finding aid itself); a segment containing the actual finding aid, which provides information about a body of archival material (a collection, a record group, or a series). Following the example of the Text Encoding Initiative (TEI), the group designated the segment about the finding aid itself the header, within which two types of information could be presented: hierarchically organized information which describes a unit of records or papers along with its component parts or divisions; adjunct information which may not directly describe records or papers but facilitates their use by researchers (e.g, a bibliography).The hierarchy of descriptive information, reflecting archival principles of arrangement, generally begins with a summary of the whole and proceeds to delineation of the parts as a set of contextual views. Descriptions of the parts inherit information from descriptions of the whole.

The mandatory EAD header is based on the TEI header. Its function is to provide a descriptive identification of the encoded archival description or finding aid. Its components are: ead id file description profile description revision description footer

This structure departs from the TEI Header in two minor respects:

The eadid is a formal, machine-processable name or address for a unique, authoritative ead instance. Its function as an internal reference identifier would normally be carried out by the global id attribute defined by the TEI. A more general idno element is also defined within the body of the TEI Header (see further below)

The footer is a note, disclaimer, warning, etc. that should be printed at the bottom of each page, displayed with each screen, etc. Again, there are several possible TEI equivalents, depending on the role or function of this note in a particular EAD application.

There are also, of course, minor differences of detail within the body of EAD header elements.

This is an example of an EAD header: jackson.sgm SHIRLEY JACKSON A REGISTER OF HER PAPERS IN THE LIBRARY OF CONGRESS Prepared by Grover Batts Revised and expanded by Michael McElderry with the assistance of Scott McLemee 1993 Manuscript Division Library of Congress

The finding aid itself contains a mandatory archdesc (archival description) and an optional add (additional materials) element. The archival description contains a descriptive identification, containing key information such as creator, title and creation date, physical description (extent, object type, etc.), repository name and department, and notes. This descriptive identification may be followed by additional detailed information such as administrative information, biography or history of people or organizations involved, controlled access headings, or scope and content of the described material.

The archival description may also contain any number of descriptions of subordinate components (dscs). These can be full descriptions, like the top-level description, or can take the form of lists or tabular displays of components.

As noted above, the CIMI DTD was developed as a domain-specific application of the generic TEI framework. As such, it uses the standard features of the TEI Header to encode core metadata about each document. Particular emphasis is placed on bibliographic information and on access information and conditions (copyright statements, credit lines, etc.)

In addition to the standard TEI Header, the CIMI DTD introduces metadata concepts which apply within the document itself.

A principal aim of Project CHIO is to provide online access to the relevant parts of documents in response to enquiries. These enquiries might come from the general museum-going public, or from museum professionals.

In order to do this, any aspects of relevance to potential queries need to be marked up. Also (less obviously) the scope of each search term needs to be made clear. If a section within a chapter describes a technique of interest (e.g. rug-hooking), then only that section should be returned to the searcher, not the whole chapter (and certainly not the whole book!).

A distinction was made between the main topic of discourse within a piece of prose (primary access points), and passing mentions of a topic (secondary access points). For example, a section of one book might be a biographical essay on Grandma Moses, whereas another book might have a passing mention of her name. Clearly, the biographical essay is likely to be much more valuable to a searcher, and so the entry person = Grandma Moses would be encoded as a primary access point within that section.

The CIMI access points were developed through study of the questions asked of museums by researchers and the general public. The Categories for the Description of Works of ART (CDWA) were also used as background.

A particular requirement of the CIMI application was to associate these access points not only with discrete documents or document sections, but also with arbitrarily small chunks of text within the document, for example to answer questions of the type Show me anything that talks about Grandma Moses. This is achieved by the use of a special purpose topic element, whose attributes specify the CIMI access point concerned, and its particular value, and whose location (in SGML terms, its parent) specifies the document fragment concerned.

For example, both a paragraph and an entire article about Grandma Moses would include an element like the following: ]]>

Thi is the method by which primary access points are encoded. The access-point attribute indicates which CHIO access point is involved. The value attribute contains the actual value of the topic. This is a completely general method, and can thus be used for a variety of designators. For example: ]]> indicates a topic of identity number = 1969.1.1.

For general (public) access the topic mechanism is felt to be sufficient. However, CIMI's Project CHIO also aimed to support a more complex Museum Point of View, for which topics alone were insufficient. Certain topic designators (date is an obvious example) have a meaning which is quite different in different contexts. There is also a frequent need to organize topics into a hierarchy. To provide this precision of retrieval, topics can be given a context. For example, this context element: ... ]]> applies the context of creation to anything inside it. So, ]]> gives the date 1860 the context that it is a creation date, rather than (say) a date of birth or death.

context elements allow the primary access concepts to be qualified more exactly, and also allow them to be grouped together to form meta-records describing objects, people, places, events. etc. As well as topics , a context elements can contain subordinate contexts, thus permitting the definition of quite complex structures of metadata.

The CIMI access point mechanism is designed to be very flexible. By providing simple building blocks, the CIMI framework allows complex statements to be built up as required.

This meta-record describes an object entitled Storm-tossed Frigate, giving its artist, date of creation and current identity number: ]]> This set of data would typically be placed just inside a section of the text which describes that object, and so would associate the following index terms with that section:access point value contextobject/work Storm-Tossed Frigate person Chambers, Thomas creation - creator ( + role = artist)date range 1825 - 1874 creation [of object]identity number 1969.11.1 current location [of object]

The CIMI approach depends on the concept of inheritance which is inherent to SGML. Each section within the document inherits the topics assigned to the larger sections of which it forms a part. Thus if a whole book is about Folk Art, then each chapter within it is also about Folk Art. If one chapter within that book is about weaving, then every section within that chapter is about Folk Art and weaving, and any topics that are specific to that section: [book-level index term] ... [chapter-level] ... [section-level] ... ]]> In this case, the div2 (section) is about Folk Art and weaving and Grandma Moses.

EAD employs a similar convention in which each level of an archival description inherits the information provided by its parent, higher-level, descriptions: The archDesc element encompasses an unfolding hierarchy of descriptive information which, reflecting archival principles of arrangement, generally begins with a summary of the whole and proceeds to delineation of the parts. Descriptions of the parts inherit information from descriptions of the whole. If all the text were stripped out of a CIMI-encoded document, the access point information that remained would have a similar structure to an EAD archival description.

The CIMI DTD is meant to support a distributed resource, with contributing documents, object records and image files physically stored anywhere on the Internet. This led to linking conventions between e.g. documents and their associated images that were both robust and flexible. TEI extended pointer conventions are used to express complex links (e.g. to a specific passage in another document).

Long-lived links should not, as far as possible, be hard-wired to a particular physical location. The location of resources is liable to change over time --- as has already happened within the lifetime of Project CHIO. Also CIMI wanted to facilitate the possibility of creating mirror sites with hyperlinks to a local copy of images etc.

In order to achieve a degree of insulation from the changes that occur in the siting and naming of Internet resources, CIMI recommends the use of formal public identifiers (FPIs) for external image files, documents, etc. A typical FPI has the form where XXX identifies the naming authority, YYY the kind of entity named (e.g. document type definition, entity set, document etc.), Name is a human-readable long name for the entity, and ZZ is the human language used for its definition. For example, the following FPI is defined for one of the TEI document type definitions:

SGML's use of entity references to identify system-specific references within a document means that only the entity definition needs to change when a different system identifier is needed. The use of FPIs within such entity definitions adds a further level of indirection, which can greatly increase portability and document independence. When FPIs are in use it is normal to define the mapping between an FPI and a real system identifier within a so-called catalog file (along with some other aspects of importance to an SGML application). The format for such catalogs is not defined by the SGML standard, but is currently in the process of definition by an influential group of SGML vendors and implementors called SGML Open.

Where it is not possible (or convenient) to create PUBLIC Identifiers for entity references, URLs are used as SYSTEM identifiers. This at least gives a form of reference which can be resolved directly by Web-aware software. Where appropriate (for example where referring to an image file), relative rather than absolute URLs are given, again with the intention of improving portability of the reference.

CIMI is not alone in having to cope with the link rot which is endemic to the current generation of distributed information systems. Its use of SGML will enable it to benefit from whatever solution is eventually found to this pervasive problem.

As they are an integral part of the TEI scheme, TEI headers are routinely found in all TEI-encoded documents. TEI encoding is widely accepted in several parts of the research community, in particular amongst those engaged in the creation of electronic libraries and text centres, in electronic publishing (for example of scholarly critical editions), and in the creation of language corpora for use in Natural Language Processing. In the US, leading electronic library projects, such as those at the Universities of Virginia, Michigan, and Indiana all use TEI headers to document their holdings. Several major text creation projects (e.g. the Womens Writers Project at Brown University, the NEH-funded Model Editions Project and many others are already committed to their use. It is hard to think of a major electronic text creation project in the academic context which would not at least start by first considering use of the TEI scheme.

In Europe, the TEI has been similarly successful, though the user profile has tended to be slightly different. For example, a number of highly visible commercial electronic publishing ventures (e.g. Chadwyck Healey's and Cambridge University Press's ) have made use of it, and the TEI scheme has been mandated for use in corpus building and language engineering projects by a series of European expert groups.

Details of these and many other TEI applications are available from the TEI applications page, maintained by the project at http://tei-uic.edu/orgs/tei/apps/

For projects using the TEI Header, it is helpful to distinguish between its role as a quality control mechanism during resource creation and management on the one hand, and its role as a source of rich information for use in resource discovery on the other.

Although the EAD framework is still in beta-test form (with the first official release scheduled for early 1997), it has already been widely adopted (at least in principle) within the US archives community. Within the first few months of alpha testing, scores of archives and libraries marked up selected finding aids. [see EAD background paper]

The EAD format is likely also to be adopted as a standard by the archives community in the United Kingdom and may well emerge as an EU-wide standard. Repositories in the United Kingdom committed to EAD include Liverpool University, Glasgow University, and the University of Durham. The Public Record Office is currently conducting a pilot project with the aim of converting their listings to EAD, and there is growing interest from the British Library and NCA in developing EAD applications.

The Library of Congress has agreed to take on the task of maintaining the EAD. It is anticipated that the Society of American Archivists (SAA) will, at the appropriate time, organize an EAD advisory committee comprising representatives from the archival, library, and museum communities as well as acting as the maintenance agency for EAD.

The CIMI framework has been developed in the context of a recently-completed research project (Project CHIO), which explored the possibilities of using SGML and the Z39.50 search and retrieval protocol for museum information. So far, only CIMI members (mainly North American, but with some European representation) have actively used the framework, although the wider museum community is well aware of CIMI's work through a series of workshops and conference presentations.

Within Europe, the Aquarelle project has joined CIMI, and plans to develop the metadata aspect of its work.

It remains to be seen to what extent the CIMI framework will be adopted by the museum profession as a whole.

Future development of the TEI is controlled by an Executive Committee. composed of representatives from the three sponsoring organizations and the two TEI editors. A larger Technical Review Committee was set up in 1996, which will take responsibility for the future development and maintenance of the TEI Guidelines. It is expected that a number of work groups will be set up to deal with specific development issues, the results of whose work will be ratified by the Technical Review Committee. This Committee will also take responsibility for the continued correction and maintenance of the Guidelines, in the light of experience gained during their use over the last couple of years. Membership and other administrative procedures of this Committee are similar to the ISO model, with particular domain-specific experts serving fixed renewable terms. (Further details are given in available from http://www-tei.uic.edu/orgs/tei/ed/edw48.tei)

The TEI has announced its intentions of setting up work groups to develop proposals on a number of specific topics during 1997. These include: extensions to the TEI Header e.g. for geospatial data, art historical information, manuscript description; further work on textual criticism, to include tags for analytic bibliography, codicology and physical description of primary sources; further work on encoding of historical dictionaries; further work on Writing System and character set problems.

The Library of Congress, Network Development/MARC Standards Office (ND/MSO) has formally agreed to serve as the maintenance agency for the EAD. As maintenance agency, LC will make the DTD and support documentation available and act as a clearinghouse for communications on the EAD, chiefly through the establishment of an electronic list and World Wide Web site.

The Society of American Archivists (SAA) will be responsible for ongoing supervision of the standard. It is anticipated that SAA will, at the appropriate time, organize an EAD advisory committee comprising representatives from the archival, library, and museum communities as well as the maintenance agency.

The CIMI Consortium itself acts as the control agency for the CIMI framework. If museums adopt the framework more widely, it is likely that one or more official museum bodies such as the Museum Computer Network, the American Association of Museums or the U.K. Museum Documentation Association will become involved, to give the framework a more neutral support platform.

The TEI design means that all the metadata is gathered up in the header, and is separate from the document. Such links as are present point to the header, either from the document (e.g. language) or from elsewhere in the header (e.g. classification system). This means that the document relies on the TEI header being present, but the header does not need the document in order to be meaningful.

The TEI scheme allows for classification of the content of a document to be accomplished at any degree of granularity, though it is easiest to do this at the text level using the textClass element within the Header's profileDesc. Finer-grained characterizations are however possible within the TEI scheme, using the decls attribute mechanism (which allows for any structural element to specify the particular set of declarations applicable to it, including its classification), or more generally by using the generic linking mechanisms. The CIMI scheme, as already noted, has similar flexibility, and was developed specifically to enable multiple levels of description.

All of the metadata describing an archival resource is stored in the findaid element. The EAD header (unlike the TEI Header) is not metadata, in that it describes the finding aid itself. It might be termed meta-metadata!

Metadata is stored partly as per TEI in the TEI header, and partly as topic and context elements nested just inside the element to which they apply. This second approach is unique to CIMI within the three schemes examined in this paper. It is an approach that might be applied elsewhere, if self-indexing documents are required.

Embedding metadata within the body of a document has good and bad points. The positive aspects are: the metadata travels with the document, and is automatically available for setting up a searchable database. current SGML databases are more likely to be able to resolve queries based on this structureThe negative aspects are: this is not metadata in the usual sense the metadata cannot as readily be verified (for example against a controlled vocabulary) the metadata is not independent of the document it describesIt should however be noted that SGML-aware conversion software can easily extract this metadata and re-express it as an separate file containing independent links (ilinks) pointing to the correct place within the source document.

Full, authoritative information on the TEI header is available in chapter 5 of the (Sperberg-McQueen 1994).

Bibliographic description: As previously noted, the fileDesc component of the TEI header is precisely designed to give full bibliographic information, and is closely modelled on existing standards in library cataloguing (op cit , p.93); It is the intention of the developers...to ensure that the information required for a catalogue record be retrievable from the TEI header (op cit p 137). Its component elements are taken more or less unchanged from analogous concepts in established bibliographic standards, chiefly the International Standard Book Description, and the Anglo American Cataloguing Rules.

Terms and conditions: Theavailability element supplies information about the availability of a text, for example any restrictions on its use or distribution, its copyright status, etc. This element can take one of a small set of predefined values for a status attribute; it can also contain a complex set of rights and conditions presented as prose. Concepts such as price and licence information are not held in analysed form, but could be included as prose description or notes. Several elements relating to distribution (for example availability and idno) are represented within a repeatable publicationStmt element within the fileDesc element, and can thus be different for different publishers, distributors, etc. of a resource. The publicationStmt element also contains information such as the name and address of the distributor, publisher, or release authority, and any associated identifier such as an ISBN or URI.

Subject terms and classification:These are recorded within the textClass element, using one or more of three distinct methods. The keyWords element can be used to supply a list of descriptive keywords, either user-defined, or from a named authority such as Library of Congress Subject Headings. The classCode element can be used to specify a value from some pre-existing classification or taxonomy, such as UDC. The catRef element can be used to specify (by reference) a value from a classification or taxonomy supplied explicitly as a classDecl element elsewhere within the header.

Together, these three methods enable very detailed subject classification information to be added using a combination of currently well understood techniques. There is however, as usual, no recommendation as to how individual projects should choose amongst them.

Bibliographic information: This is not a prominent feature of EAD. The EAD header provides a brief characterization of the finding aid itself, not the source archive. There is an ADD element, defined as follows: adjunct to descriptive data. Optional. Provides for adjuncts to the descriptive information. This is information that will assist in the use of the archival material, but is not itself archival description. One of its components is an optional bibliography element, which in turn contains a bibRef for an actual citation. This element has a loose content model, analogous to the bibl element in TEI. It allows for a reasonable degree of bibliographic description, but does not attempt to enforce any particular level of description.

Terms and conditions: information is held within accessRestrict and useRestrict within the adminInfo element. accessRestrict contains information on gaining physical access to the material, while useRestrict describes what restrictions apply to the allowed use of the material once physical access has been gained. These are optional elements, that can appear within the description of a component of the archive at any level. No guidelines are offered on the preferred structure and content of these elements.

Subject terms and classification: these are comparatively detailed within the EAD scheme. A number of specific elements are defined, grouped within the controlaccess element, so named because it contains controlled access terms. Each of these has a specific tag such as: corpName An organization or group of people that is identified by a particular name and that acts, or may act, as an entity. geogName A proper noun identifying the name of a geographical place, natural feature, or political jurisdiction. occupation Occupations (including avocations) that are significantly reflected in the materials being described. subject Specifies a subject term. genreForm Types of material distinguished by intellectual content or physical characteristics. These specific tags can be mixed in with a free text subject description, which rather complicates their usability for automatic topic extraction purposes.

Bibliographic information: CIMI records are conformant TEI documents, and can therefore use exactly the same components for detailed bibliobliogarphic description as discussed above for TEI.

Terms and conditions: Again, CIMI records can use the same components for this purpose as discussed above for TEI.

Subject terms and classification: Again, CIMI records could use the same components for this purpose as discussed above for TEI. However, the mechanisms available for linking text classification information to particular parts of a document were judged inadequate or too complex for use in CIMI. The CIMI application therefore extended the TEI scheme (using the TEI's built-in customization mechanism) to include two special-purpose metadata elements which can be anchored at any point within a document, with local scope. These elements (topic and scope) were discussed above, in section .

This table summarises how some broad metadata features are covered by the three schemes examined:Attribute TEI EAD CIMIBibliographic fileDesc add bibliography bibref fileDescTerms and conditions publicationStmt availability adminInfo accessRestrict useRestrict publicationStmt availabilitySubject terms, classification profileDesc textClass controlAccess topic optionally qualified by context

The guidelines for creation of independent headers within the TEI scheme give some indications of parts of the Header to which such constraints are likely to be of importance: where there is a choice between a prose content model and one that contains a formal series of specialized elements, wherever possible and appropriate the specialized elements should be preferred to unstructured prose Similarly, in the discussion of the titleelement: The level attribute must be used to indicate whether this is the title of a book, journal, or series. It is highly recommended that the type attribute be used to distinguish the main title from subordinate, parallel, or other titles However, even in the case of independent headers there is no indication that the syntax or vocabulary of entries should be constrained in any way.

EAD makes no recommendations for the actual syntax or vocabulary of any textual element. This is a typical instruction (for the corpName element):This element contains text and may contain any elements found in the Linking and Formatting Elements, as many times as needed.

However, the instructions for entering the attributes which provide metadata about the corporation name are much more specific: role Used to specify the relation between the name and the item being described. The value supplied should be a word or phrase taken from the USMARC relator code list. sources Used to indicate the source of the controlled vocabulary term contained in the element. Possible values are: aat (Art and Architecture Thesaurus) aacr2 (Anglo-American Cataloging rules, 2d ed., rev.) dot (Dictionary of Occupational Titles)

CIMI shares the general TEI approach to content within the TEI Header. However, within its topic and context elements it provides more specific guidance, by proposing a set of specific values for the access-point attribute on the topic element, and the CHIO attribute on the context element. In both cases, the values are drawn from a closed list, itself compatible with the CIMI Z39.50 profile attribute set. Even here, however, there is an alternative mechanism for context which lets you declare other contexts as a value attribute, with a corresponding authority; this extensibility is further discussed in the next section.

The actual value of the topic is not constrained.

As noted above, the TEI scheme is designed to provide a framework which can be customized and extended to suit the user's exact requirements. Users can define their own custom tags, rename TEI elements to a form that is more acceptable within their community, define a new base structure for their information, undefine existing elements, modify content models etc. The published TEI Guidelines include examples of approved extensions which were developed along with the Guidelines themselves.

Within this general framework, the TEI Header is rather less easily extended than other parts of the DTD. If additional concepts are required, the existing elements that are to contain them need to be undeclared, then re-declared with their amended content. This is rather less elegant than the standard methods for adding to a class of existing elements within the document itself, but functional.

In general, modifications to the header are associated with the selection of tagsets from the TEI scheme which imply that these predefined modifications will be needed. For example, one of the effects of selecting the TEI's predefined tag set for language corpora is to extend the TEI Header, by including tags for documenting demographic and other characteristics of the participants in a written or spoken text. Another is to add a fourth way of classifying texts, in terms of their situational parameters.

Another example is provided by work currently in progress at the Bodleian library, where a rich set of descriptive tags for components of a traditional manuscript description has been defined, and grafted into the existing TEI Header structure, simply by redefining the encodingDesc element to include a new mssDescription element.

We cannot find any suggestion that the EAD has facilities that would allow users to extend the DTD.

Insofar as CIMI records use the TEI header, the above remarks apply. In the specific area of subject classification, both the topic and context elements have been designed to accommodate an open-ended set of descriptors. For example, context has a CHIO attribute which contains a fixed list of the CHIO context access points, but it also contains a pair of attributes value and authority, which can be used together to provide a context taken from any authoritative source. This has already been used to encode museum concepts which do not happen to fall within the CHIO scheme: ]]>

Thus two levels of extensibility are available. An open-ended range of classifications can be encoded using the existing framework. And it would always be possible for CIMI to extend its own fixed list of contexts and access points.

As noted above, there have already been proposals for the extension of the TEI Header to handle the specific requirements of manuscript description: a recently-organized conference surveyed a range of activities in this area (see the Studley Manuscript Encoding Meeting ). One of the workgroups to be set up by the newly chartered TEI Technical Review Committee will address this and related issues of extending the TEI Header in a controlled manner.

It also seems likely that the definition of a set of Guides to Good Practice in the application of the TEI Header to a range of materials, at least to the kinds of textual material held at electronic text centres, will consolidate existing and newly-emerging consensus on how best to make use of its flexibility.

The current version of EAD is undergoing beta-testing: presumably all development efforts will go into releasing the first official version of EAD. It is probably too early to say what will happen subsequently, but existing use of the beta version (and commitments made to testers) already limit the ability to change the EAD scheme in a non-upwards-compatible manner.

The CIMI framework is less finalised than either TEI or the EAD scheme. CIMI will review the results of Project CHIO, and has an open mind as to how the format might develop. The lack of any significant deployment does give CIMI the flexibility to change its mind. It has a keen desire for interoperability, and plans to talk to both EAD and TEI about this.

The Dublin Core is a currently much discussed set of metadata elements, which is increasingly regarded as providing a useful basis for general purpose resource discovery activities, particularly with networked resources. It has the merit of defining a small number of very generally applicable concepts, into which almost any more elaborated set of metadata concepts can readily be mapped. Examples of mappings between Dublin Core and EAD, and Dublin Core and GILS amongst others are available from Miller 1996; we list a similar cross-walk for the schemes discussed here: DC heading TEI EAD CIMISubject textClass controlAccess topic contextTitle title titleProper titleAuthor author author authorPublisher publicationStmt . publisher publisher publicationStmt publisherOtherAgent sponsor funder principal respStmt resp editionStmt resp sponsor funder principal, respStmt resp editionStmt respDate publicationStmt date publicationStmt dateObjectType textClass keywords textClass keywordsForm SGML; implied SGML SGMLIdentifier publicationStmt idno publicationStmt idnoRelation Source sourceDesc biblFull sourceDesc biblFullLanguage langUsage language langUsage languageCoverage extent extent

Chapter 24 of the TEI addresses specifically the question of mapping the components of the TEI fileDesc on to corresponding MARC fields. The mapping defined there implies that automatic conversion would be difficult, even though each data item would be in an appropriate MARC field or subfield. For example, there is no provision for the 'Main Entry' (or USMARC 1XX fields) in the TEI header. The main entry should be manually constructed by the cataloguer, using appropriate name authority control, and human intelligence to select from the information given in a TEI header the agency primarily responsible for the intellectual content of the work. There is an author tag, but the form of the name would have to be checked by a cataloguer before the main entry was constructed. Specific sets of values for the TEI defined attributes would need to be enforced before the TEI tags could reliably differentiate between name, conference, or title series; in their absence there is no simple mechanical method for determining which MARC tag (410, 411, etc.) should be used for series title and idno. Safe practice would be to load any series statements into 490 fields, and then to conduct authority work on those fields.

Since that date however, there has been considerable progress: for example, with the definition of the 720 generic author field, some of the above difficulties are removed. In a report commissioned by the Oxford Text Archive (Giordano 1996) a detailed mapping between the TEI Header and USMARC is proposed along with some more tightly specified cataloguing practices which together make feasible automatic loading of TEI Headers to USMARC records. The paper demonstrates that it is possible to create valid MARC records directly from SGML-encoded metadata, by defining a set of local practices and conventions in addition to the constraints enforced by the SGML document structure.