Enabling Accessible Resource Access via Service Providers

Alexander Haffner and Gerhard Weber Human-Computer Interaction Research Group

Technical University of Dresden Nöthnitzer Straße 46, 01187 Dresden, Germany

{alexander.haffner, gerhard.weber}@inf.tu-dresden.de

Abstract Libraries have become digitized and are using information technology for storing and managing their resource inventory. Additional metadata are used for describing properties of non-digital assets as well as of purely digital resources. In particular, as the amount of digital resources increases, there is demand for centralized services for searching and distribution of content. Stakeholders of libraries and publishing industry already have made progress in areas of archival strategies and standardization of preservation strategies. A variety of metadata standards and exchange protocols enable service providers to offer a single access point to resources. However, there is still an increased demand for improvement of resource organization and enhanced quality particularly in terms of accessibility. This paper presents strategies to increase accessibility of resources as a valuable step towards access-for-all. For consideration of accessibility within the publishing chain we analyse the whole processing chain and identify stakeholders such as national libraries and their corresponding responsibilities for ingest, archival storage and dissemination of digital resources.

Keywords library-for-all, cataloguing, accessibility metadata, collaborative accessibility

Introduction Libraries are in charge of knowledge access provision to people no matter where they are from, what social background they have and of course no matter what their reading skills are. The development of digital archival information systems expelled libraries in performing their respective duties. By establishing digital libraries all over the world, information exchange between wide-ranging organizations has stepped up and even people, who never saw a library in life, suddenly got an opportunity to access high quality information through the World Wide Web. Advantages of digital document distribution via internet in comparison to traditional library operation are obviously. But the question is, did really all users get access to libraries or is there still some reader group not accounted for? Immediate answer is, there are such referrers, i.e. everyone who is not able to access the internet, but these people are not the only ones. A variety of users do not have the necessary skills for accessing mainly textual electronic resources in their designated modality of use. A variety of publishers faced this issue and consequently produced equivalent alternatives. Examples are digital talking books for the blind, large print for visually handicapped, titles containing sign language videos for deaf or publications in simple language for dyslexics. So actually, somewhere is more or less content for everyone. Unfortunately we have to emphasize the word “somewhere”. Catalogues for alternative equivalents are as well as corresponding archival systems almost completely independent of electronic library catalogues. Furthermore each alternative content provider is focussed on the provision of disability specific materials, as a consequence, even publishers of alternative formats among each other are not properly connected. This paper will have a closer look on state of the art of library connections, as well as capabilities for identifying and specifying resource relationships between primary resources and equivalent alternative resources for a common approach to cataloguing. Our approach to such relationships is based on exchange and interoperability strategies of applicable metadata and describes corresponding organizational frameworks bringing together content producers, librarians, accessibility experts and of course all kind of end users.

State of the Art in Library Environments To search and find items card catalogues have been a familiar sight to library users for generations. Since the upcoming of computer technology, libraries discovered vantages in comfortable catalogue entry exchange via electronic data. Data migration in electronic catalogues took a while and is still a

work in progress. For example, the Saxon State and Dresden University Library expects to finish digitalization in 2013. From then on the catalogue includes the complete in-house inventory (approximately 9 million items) and beyond that, catalogue entries of massive inventories of resources provided by third party sources. The example illustrates the responsibility of archives in descriptive cataloguing and subject cataloguing. Due to standardized cataloguing rules, like Anglo-American Cataloging Rules, 2nd Edition, (AACR2) or in the German-speaking world the Regeln für alphabetische Katalogisierung (RAK) for descriptive cataloguing and Library of Congress Subject Headings or Regeln für den Schlagwortkatalog (RSWK) in Germany, libraries have a feasibility for subsequent use of already specified catalogue entries. The base for cataloguing exchange is set by metadata. Metadata is structured information, they describe, explain, locate, or otherwise make it easier to retrieve, use, or manage an information resource [1]. Metadata is used to describe the context, content and structure of assets. By applying several standards like MARC 21 [2], MODS [3] or MAB2 [4], libraries can represent and communicate bibliographic and related information in machine-readable form. Metadata formats provide standardized fields or elements to reflect the content of catalogue entries. Commonly, libraries describe primarily single resources with little consideration to similar and related resources. In particular, their exchange is established by several software manufacturers and enjoys widespread usage as long as the same software application is used. The Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH) [5] provides an application-independent interoperability framework based on metadata harvesting that differentiates data providers (administer systems that support OAI-PMH as a means of exposing metadata) and service providers (users of metadata harvested via the OAI-PMH as a basis for building value-added services). Consequently, each library performs in-house cataloguing to expose the corresponding metadata for a more general data collector like union catalogues or national libraries. The German National Library as a harvester complies with this approach outlined by OAI and collects metadata from libraries, publishers and retail repositories to create a global access point in search by end users. The data exchange between traditional libraries is highly organized and works very well in Germany. The data exchanged cover bibliographic entries for non-digital as well as metadata about digital resources. As already mentioned, metadata standards are used successfully among libraries whereas MARC 21 is elected to be the exchange format for all libraries in Germany and Austria in foreseeable future [6]. Retail and publishers draw on enhanced metadata standards to represent commercial facts of interest in addition to pure bibliographic data. Therefore the most representative standard is Online Information eXchange (ONIX) [7]. It appears producers of accessible alternative resources are still an exception in this networked process. Producers of primary resources are obligated by law to notify the national library about every published resource (print or digitally born). In the alternative resource production domain producers only have to announce Braille prints thereby a considerable inventory of accessible materials are not centrally registered. However, German libraries for the blind did a first step in this direction. Medibus [8] is an organisation formed by publishers of assets for blind people. Medibus has guided producers of suitable resources for blind and visually handicapped users to harmonize and union their cataloguing. The common catalogue will integrate bibliographic entries of German, Swiss and Austrian publishers. But, catalogue operators do not intend to expose the metadata. Furthermore the operators did not select any metadata standards for automatic exchange yet. Currently, librarians have to submit bibliographic entries by e-mail and Medibus manually double-checks all entries provided for conforming to cataloguing rules. The situation is in the field of sign language video production less developed, and accessible resources are disseminated independently with a few exceptions [9]. It appears, sign language video producers are excluded of networked cataloguing and work separated of other stakeholders in production. In the following we describe a common approach suitable for all providers to offer readers global access points in which they get an opportunity to search and retrieve all information available on the market and in libraries. They should not have to care if assets are accessible, and explore entries in a structured way to identify and access an item matching their needs.

FRBR Model and Resource Description and Access (RDA) The growth of shared online catalogues with international scope and increased use of digital archival systems reduced cataloguing costs by minimizing duplicate cataloguing effort. But the emergence of new forms of electronic resources and new information contexts induced additional requirements for cataloguing principles to match accompanying adapted end user needs. A model for cataloguing has

to identify and clearly define entities of interest to users by bibliographic records, the attributes of each entity, and the types of relationships that operate between entities. The Functional Requirements for Bibliographic Records (FRBR) Model is a conceptual entity-relationship model developed by the International Federation of Library Associations and Institutions (IFLA) which exactly achieves this challenge. The basic elements of the model (entities, attributes, and relationships) were derived from logical analysis of the data that are typically reflected in bibliographic records [10]. Key objects that are of interest to users cover textual, music, cartographic, audio-visual, graphic, and three-dimensional materials in non-digital and/or digital form. FRBR defined tasks that are performed by users when searching and making use of catalogues. Bibliographic records are used to find materials that correspond to the users stated search criteria, to identify an specific entity, to select an entity that is appropriate to the user's needs, and to acquire or obtain access to the entity described [10]. Each of the entities defined for the model serves as the focal point for a cluster of data. The model divides entities into three major groups:

• group 1 comprises products of intellectual or artistic endeavour that are named or described in bibliographic records: work (a distinct intellectual or artistic creation), expression (the intellectual or artistic realization of a work), manifestation (the physical embodiment of an expression of a work), and item (a single exemplar of a manifestation),

• group 2 comprises those entities responsible for the intellectual or artistic content, the physical production and dissemination, or the custodianship of such products: person and corporate body,

• group 3 comprises an additional set of entities that serve as the subjects of intellectual or artistic endeavour: concept, object, event, and place.

FRBR is built upon relationships between and among entities. Relationships among entities in the first group are obvious. However, there are as well relationships between entities of heterogeneous groups. For example relationships between group 1 and group 2 are specified such as a work is created by, an expression is realized by, a manifestation produced by and an item owned by one or more than one person and/or corporate body. Entities of group 3 serve as subjects for the work but also can all entities in the first and second group serve as subject for works. A work is an abstract entity which aggregates appropriate intellectual or artistic entities. We want to use this approach to unify traditional non-digital, digital and equivalent alternative resources of every kind in just one global catalogue-for-all under the usage of adequate cataloguing, according metadata and corresponding organisational frameworks. As a clarification to the model, Figure 1 outlines how Dan Brown’s bestseller ‘Angels & demons’ is applied to the introduced principles for this specific work including primary and alternative resources.

Figure 1: Unified bibliographic records according to FRBR Model As global access point for a work the title and creator information allows users to locate all available realised expressions. The example firstly illustrates a textual expression of the original edition which is produced by two different content producers in two different forms. Both, a print version and an electronic resource exist. The Braille print is not treated by FRBR as text. Braille is considered like

work: Angels & demons / Dan

expression 1: original edition …

expression 5: Illuminati / German translation by Axel Merz

expression 2: audio book / narrated by Richard Poe

expression 3: Braille print

expression 4: Digital Talking Book / narrated by Jack Fox

manifestation 1a: Angels & demons / Dan Brown. New York, Pocket Books c2000. (430 p., maps, 25 cm) ISBN: 0671027352

manifestation 1b: Angels & demons : [ebook] / Dan Brown. New York, Atria Books 2004. (Adobe PDF, 899 KB) ISBN: 0743412397

manifestation 4a: Angels & demons [sound recording] / Dan Brown. Washington, D.C. : National Library Service for the Blind and Physically Handicapped, Library of Congress, 2006. (APH, recording studio, 17 hours, 27 minutes) DB 51799

translations from one language to another, thus it is catalogued as a separate expression. The audio book and digital talking book are clearly differing forms. An audio book is auditory only whereas a digital talking book can be consumed auditory or visually. Digital talking book manifestations as the physical embodiment of an expression could also diversify. For example, a publisher may have separated one manifestation to be placed on several CD’s and kept a second version stored as a whole for download. Each manifestation itself is represented by a variety of items owned by someone. Items can be books in a shelf likewise copies of computer files. Resource Description and Access (RDA) is an upcoming user-focused content standard for the increasing digital world which changed perspectives of cataloguing from a catalogue user looking at the record in isolation to a user seeking the record within the context of a large database or catalogue [11]. This approach is enabled by the conceptual re-use of the FRBR model and also by the one expressed in the Functional Requirements for Authority Data (FRAD) model [12]. A first release of RDA is announced for early 2009. Since Mid-October 2008 is a full draft available by the Joint Steering Committee website [13]. RDA is a content standard guiding librarians and non-librarians how to describe resources and their relationships. RDA does not provide guidelines how to display information to users or how to exchange recorded information between interested organizations. But the logical consistency of RDA allows metadata communities the specification of adequate standards to create well fitting metadata interoperability. Communities already aim at a first realization of RDA records in MARC and Dublin Core. To increase RDA’s usefulness as an Internet metadata content standard, work is currently underway toward developing an RDA application profile and an RDA element vocabulary [11]. RDA is also intended to meet publisher needs. Initially, it is an advantage if non-librarians start cataloguing by applying the same content standards as professional librarians. Moreover, the organizations responsible for RDA development may select suitable properties (such as defined by ONIX) for complete standard matching. RDA guidelines have been constructed to lead the cataloguer through a logical decision process. Initially, cataloguers describe entity attributes defined in FRBR and FRAD and in a second step their relationships. A particular feature of RDA is its ability to record relationships between works, expressions, manifestations, and items. Relationships between one manifestation and another can be very helpful to identify resource derivation and corresponding accessibility properties.

Metadata Categorization In addition to the importance of metadata for data exchange and resource management it is necessary to list types of metadata to identify those types are properly covered by established standards and those still detached. By NISO definition [1] there are three main types of metadata:

• descriptive metadata describes a resource for purposes such as discovery and identification, • structural metadata indicates how compound objects are put together (internal structure), and • administrative metadata provides information to help managing a resource.

Furthermore there are two subsets of administrative metadata that actually have to be considered separately:

• rights management metadata dealing with intellectual property rights, and • preservation metadata containing information needed to archive and preserve a resource in

the long-term (including technical metadata). In addition there is still a need for two further categories:

• marketing and retail specific metadata which supports commercial resource distribution, and • accessibility metadata which identifies adaptability of resources and relationships between

primary and equivalent alternative resources on various levels of granularity. Descriptive metadata as predominant metadata type for description of non-digital and digital resources is definitely covered by a wide range of metadata standards. Structural metadata is mainly applied by describing digital resources because without structural metadata, the page image or text files comprising the digital work are of little use. Administrative metadata in particular technical and preservation metadata finds more and more usage in archival information systems intending long-term preservation for future access. A representative standard for holding descriptive, structural and technical metadata is the Metadata Encoding and Transmission Standard (METS) [14]. METS is a hierarchical format and made for digital resource description. METS is extensible for the integration of further standards that for example allow internal usage of long-term preservation metadata like

PREMIS [15]. Administrative metadata is also an opportunity to specify rights management metadata but until now there are no established standardised formats. As already mentioned above is ONIX a well working format to record marketing and retail specific metadata. Our particular interest is in accessibility metadata standards. A specific kind of accessibility metadata is IMS AccessForAll Meta-data (ACCMD) and Accessibility for LIP (ACCLIP user profiles). ACCMD was developed to describe accessibility aspects of learning resources. On the contrary ACCLIP describes the needs of users in consuming documents. ACCMD categorised resources by two major types: primary resources and equivalent alternative resources. The primary resource is the initial or default resource. An equivalent alternative resource provides equivalent semantic and behavioural functionality [16]. Equivalent alternative resources can cover the whole primary resource or only some parts. Primary resources have to declare global access modalities. Additionally, a primary resource needs metadata about adaptability regarding display transformability and control flexibility, and of course metadata about existence of equivalent alternative resources. Equivalent alternative resources can supplement (i.e. captions for a video) or substitute (i.e. DTB substitutes a PDF) a primary resource. Corresponding metadata declares the nature of the resource equivalence, the substituted access modality, and its own modality of use. An upcoming cross-domain accessibility metadata standard is Dublin Core AccessForAll (DC-AfA) [17]. DC-AfA builds up on the approaches in IMS specifications. In other contexts, there are specifications and standards for the structuring, encoding and organisation of content that aim to improve the accessibility of that content. The AccessForAll approach is concerned only with descriptions of the resource by making explicit any accessibility characteristics [17]. Advantages of accessibility resource labelling by DC metadata are in the re-use in any existing DC resource description. Beyond the replacement or augmentation of alternative and original resources (hasAdaptation / isAdaptationOf) the metadata set intends to use refinements of DC terms like hasFormat / isFormatOf (second resource presents the same content as in another resource in a different format), hasPart / isPartOf (resource has or is a component of another resource), and conformsTo (resource conforms to defined guidelines). Furthermore the specification of language, format, type, and education level ought to help finding best fitting resources. The property values itself will be provided by recommended vocabulary. At this stage we would like to emphasize that accessible resources match particular user needs resulting from their choice of devices, user agents, circumstances or perhaps a disability. Consequently accessibility metadata is not only providing disabled users rather it can support a wide-ranged target groups.

Document Processing Chain The actual document processing chain can involve concepts of accessible content production and distribution if provisions are made. The OAIS Reference Model [18] recommends in particular three major sub-processes ingest, archival storage and dissemination. We describe in the following an organizational framework as candidate for implementing accessibility within theses sub-processes.

Ingest Issue For an optimized ingest the archival administration has to state standards for resource (document) production as well as metadata design. Accessible creation of mainly textual documents can be approached by the supply of authoring guidelines and templates which ensure accessibility as a specific quality characteristic at an early stage. Consequently publishers have to force authors keeping track on probably publisher refined guidelines as assumption for a publication. Publishers are mostly established organizations to expect a high resource quality. Consequently, handed material has to be overworked by in-house accessibility experts to meet user needs before final ingest into an archive. On the other hand authors publishing publisher-independent via a libraries cannot be forced to generate at such a quality level. Best applicable solution could be ingesting source documents (i.e. Office document) which match minimum accessibility guidelines based on templates to perform an internal representation transcription (i.e. into PDF) by an archival system. Professional equivalent alternative resource producers are well skilled and aware of specific user needs while ensuring high resource quality. But in consideration of Web 2.0 development, we have to discuss actual end users changing into author role too. The idea behind steps towards collaborative accessibility enrichment. If users provide supplementary information to already existing content, like alternative image descriptions or video captions, they need content production guidelines too.

Second major issue for accurate ingest besides resource quality is in metadata enrichment. Metadata provided by publishers and authors must chiefly cover a prescribed set of descriptive metadata. Assistive cataloguing systems can support content specification in accordance with standards like RDA. Therefore archival information systems have to externalize consisting metadata to re-use existing entities and to structure new records into it. Publishers probably run local cataloguing systems using externalized metadata. These systems expose locally recorded metadata to hand the enriched set back to archives and service providers. Archival systems should as well offer web-based interfaces to support publisher-independent authors in metadata enrichment. However, librarians will ever have to control and extend handed metadata by additional information and further metadata types to match the full cataloguing needs. A FRBR-conform cataloguing at descriptive level increases resource retrieval at all and provides an ideal enhancement for accessibility metadata. Mandatory accessibility metadata should always be indexed by qualified staff. Relationships between manifestations identify kind of derivations. Each entity (for primary and equivalent alternative resources) has to be tagged by information about adaptability regarding display transformability and control flexibility. Furthermore, manifestation need precisely stated access modalities and if applicable the substituted access modality. Accessibility experts are in charge of manifestation-comprehensive tagging at a touched work to define necessary accessibility relationships. Accessibility-tagging still needs manual checking but is supportable by intelligent automatic evaluation methods. By subsequent use of structural metadata, equivalent alternatives are possibly referenced by partial resources. Resulting, accessibility experts have to refine structural metadata regarding physical (files) and logical level (pages, paragraphs, integrated images). Of course non-professional accessible content providers can extend corresponding metadata too but experts have to double-check this information as well as descriptive metadata.

Archival Storage and Accessible Resource Identification Without emphasising actual physical storage principles focus on the accompanying data management. This management takes place in local databases but gets reflected by exchangeable metadata too. The OAIS Reference Model defines the term Archival Information Package (AIP). AIPs may bundle a multitude of resources in combination with preservation description information. Our approach intends to hold complete metadata and locally stored resources to a whole work in only one AIP. This approach enables the decomposition of corresponding physical data to a specified access point defined by the content standard. The data set to a work and its externalization allows access by third party systems and consequently adequate package enrichment by content and metadata extension. We are considering METS as a nesting standard and DC terms for the representation of an AIP and developed a contrivance metadata scheme to define FRBR relationships for integration in the descriptive section of METS. Furthermore we combined descriptive and accessibility metadata to ensure resource usage fitting user needs. Currently we are facing lack of structural metadata for non-digital resources as METS is originally made up for digital resource description only. Nevertheless, our concept is progressive. A variety of communities develop metadata schemas representing RDA conform information. If these metadata become standardized we can enrich one of the metadata schema’s accordingly. In respect to accessibility, the system can decide whether a resource provides characteristics to meet user abilities. The system then may conclude if a resource has to be adapted, avoided completely or just in parts, and thereupon substituted. Our target is that an archival system besides traditional functionalities must identify which resources are related to which alternatives and how the benefits for a specific user and his context can be maximized.

Dissemination The first goal in accessible resource dissemination is the design of an accessible user interface. As, for example, the WCAG guidelines describe a variety of implementation mechanisms, we concentrate on the actual access to resources accessing. The access to works searched and found in catalogues can in principle be illustrated by two scenarios: Scenario 1: A user knows without any assistance what resource type he is looking for, so it is mandatory to represent all expressions to a queried work by displaying user-relevant metadata. The user will then be able to select an expression of his choice to explore manifestations included. If finally the access modalities of a manifestation match his needs he can start the process of obtaining single items.

Scenario 2: The user does not know exactly which resource type to choose for his intended purpose. In this situation, adaptive content processing should be applied. During archive registration, users register their user profile which holds abilities and disabilities regarding document reading. Consequently, the system can adapt sub-item’s display and/or control to match specific user needs. If not possible, i.e. caused by resource limitation, the system needs the ability to look autonomously for alternative equivalents that provide the preferred modalities of use. Furthermore, the user should be guided by a pre-defined tour that leads him on a usable navigation path through pre-selected accessible resources. Accessible resources and the related tour description could be delivered as a prefabricated Dissemination Information Package (DIP). Additionally, the system is able to integrate necessary software modules for proper execution. In both scenarios metadata for works as access points is used to find and explore the global catalogue entry. The extended information to underlying entries enables decision making regarding personalized reading process. Scenario 2 illustrates how a system can use hierarchical and extended metadata to identify best fitting resources to match user needs. But we want advert a hazard. In automatic resource selection user can miss up-to-date information. For example if an accessible manifestation is available only in an older edition users have to be pointed to this fact. Probably, they will consume the accessible resource because they do not have a choice but it is important to have the information about this situation. Besides online resource access, online digital resource representation is a growing quality characteristic. If users fulfil their document consumption in a closed environment, intelligent systems can adapt representations to user needs. Additionally, accessible resource dissemination is without notice performable. As according representatives [19, 20, 21] introduce web-based interfaces for accessible multimedia playback. Current prototypes are dissociated from archival information systems but could be fit really well in.

Organizational Framework Today, distributed archiving is already state of the art. Publishers of usual resources as well as producers of accessible alternatives can store resources physically independently (in house or in external archives). However, critical part of the process chain is the reporting of metadata to bring together products of all participating producers, and additionally offer access to these metadata as service provider. For example the German National Library as the overall German service provider has to collect data from providers such as publishers, from a variety of traditional libraries, and from accessible resource producers like libraries for the blind. All the mentioned organizations are required to use equal content standards and metadata standards in cataloguing and according management systems to provide a smooth data exchange. Also the National Library will be in charge for a global metadata collection and externalization to third-party systems to ensure proper re-use and accurate metadata integration. Libraries as providers of big archival information systems work in general similar. Thereby electronic library catalogues become hierarchically organized, too. National libraries are in a centralized position. Underlying catalogues are unified catalogues consisting of metadata for state-comprehensive inventories. Metadata for unified catalogues is provided by chiefly state libraries and as well municipal libraries. Each archival information system acts as data provider to expose metadata for underlying and superior systems. Additionally each system serves users as a service provider by an institution-comprehensive catalogue access. Consequently, we decided to discuss one exemplary archival information system and according structures for a fitting organizational framework beyond the introduced library system hierarchy. The following Figure 2 illustrates relationships between an archival information system providing accessible resources and a variety of data providers. Accessibility evaluation (AE) involves qualified staff that controls and specifies resource accessibility itself and relates primary and equivalent alternative resources on a metadata level.

provider of print resources

provider of ebooksprovider of digital talking books in DAISY format

provider of Braille print resources

provider of sign language videos

archival information system

ingest

cataloguing by content standard

accessibility enrichment

publisher-independent content provider

dissemination archival storage

data provider

service provider

AEAE AE

AE

AE

AE

AE

end user

Figure 2: Content and metadata providers to an archival information system Every resource provider ingests a type of resource. Consequently, each resource provider has to specify the type and of course all additional necessary descriptive metadata to perform a content standard conform cataloguing. We already mentioned that it does not matter if content providers use own cataloguing systems transferring according metadata or perform the cataloguing by user interfaces in the archival information system. For professional content providers it is recommendable to employ accessibility experts dealing with structural metadata and associated accessibility information. Accessibility metadata is not required to have been made by the same resource provider as the content or even to be located at the same location. An accessibility expert has to enrich the complete metadata set about a particular work keeping all expressions and manifestations in accessibility relationship to support reasoning about the best user provision in their modalities of use and corresponding access modalities. Furthermore, manifestations have to be segmented in logical or physical parts that must refer to partial manifestations in differing types, too. That means a metadata set has to provide relationships between primary and equivalent alternative as well as among alternative resources. Unfortunately, a lot of resource providers are not able to add qualified accessibility metadata. Consequently, established data providers must engage accessibility experts to accompany the process to ensure considerable accessible resource access. Alternatively, publisher-independent accessibility experts could handle accessibility metadata enrichment to substitute missing skills of some resource providers or archival information system operators. However, role change by users is more and more present and actual end users are welcomed to overtake authoring in various communities. Is this approach applicable to archival information systems too and could it entail a quality incensement? Firstly, we have to point aspects of rights in a digital library. Content and resources are owned by producers or providers and consequently protected from manipulations. So a user cannot change any content itself, and this never should be intended, but users can enrich resources by additional information referenced by metadata. We advocate a new approach, called Social Accessibility or Collaborative Accessibility, to make existing content accessible by using the power of an open community [22]. Collaborative accessibility enrichment allows users to annotate existing content by accessibility information as well as the production of their own accessible resources corresponding to existing primary work. Often users experiences similar obstacles and find ways to overcome those. For example, blind users scan their own books and share the resulting electronic version (www.bookshare.org). For annotations, users need a resource presentation interface that allows comfortable attachment of additional information like alternative image descriptions without any knowledge about cataloguing or metadata. If librarians structure a primary resource by structural metadata, annotations will be treated as supplementary resources and be assigned to specified sub-resources or resource parts. The production of equivalent alternative resources by non-professional users is much more prone to reduced qualitiy. Non-professional producers need guidelines and templates to reach a high quality for their resources, and in addition support by accessibility experts relating manifestations and content standards. A different accessibility enrichment approach is based on automatic production of equivalent alternative resources. Tools generating automatically accessible resources enter market and especially are distributed by open source communities. As example, we want to mention the DAISY pipeline [23] as production framework for digital talking books in DAISY format. The included filter

techniques are well qualified for subsequent use in archival information systems to perform quick and economic resource transcription on the fly. Filters always start work at structured source documents (i.e. XML based Office or LaTeX documents). Additionally, filters can generate PDF as standard distribution format regarding textual documents, and furthermore, generate automatically corresponding structural and technical metadata. In correspondence with manually enriched descriptive metadata manifestations to a particular work establish in a variety of types and provide accessibility for a wide-ranging user group.

Conclusion Centralized search interfaces allow significantly more appropriate access in particular by people who have to use varying types of resources. Exploration in heterogeneous digital libraries by a single access point will be the future for all users. In particular users with special needs benefit from a wide-ranging choice and adaptable resources to provide modalities use with respect to their reading needs. We highlighted the exigency for metadata to establish some of the underlying relationships. Organizational approaches for an increase of equivalent alternative resources in archives have to be strengthened. No matter who ingests resources, public interest has to ensure advantages of accessible alternatives are spread more widely and affect everyone’s life. Professional publishers have to understand the commercial impact of accessible resources for varying contexts besides actual primary resources.

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