Design and Development Model of a Web Accessibility Ecosystem

Abstract

The article examines issues of web accessibility ecosystems for people with special needs. Methods, models, accessibility standards, and technologies related to the structure, design, and functionality of the web accessibility ecosystem are studied. The stages of developing an accessibility ecosystem are explored. The accessibility of the design, functionalities, structure, and content of a particular ecosystem are presented. Several themes for the design of the system with an emphasis on its accessibility for blind users are explored and analyzed. UX/UI design and the ontological model of accessibility, used in the implementation of the model of the ecosystem and its elements, are studied. A web accessibility ecosystem model has been developed, compliant with the Web Content Accessibility Guidelines and based on semantic technologies. Other qualities of this model are easy access to information resources on the topic of accessibility, convenience for users with different needs, and the possibility of expansion and enrichment in the future.

1. Introduction

Research into the problems of the accessibility of the digital environment for people with special needs is particularly relevant due to the rapid development of modern digital technologies and communications. More new methods are being developed for the digital accessibility of digital objects and data, the creation of innovative methodologies for building accessible environments, accessible artificial intelligence, and others. With this rise of digital and assistive technologies, not least is the issue of developing socially-oriented accessibility ecosystems.

Some of the more common systems solve a specific problem in providing accessibility. For example, for the ARCHES system (a European Union-funded heritage project), a study was conducted that investigated activities that allow people with visual or cognitive problems access to content in the archives of the European Union [1,2] and guidelines for the creation and organization of accessible digital learning resources are presented in [3].

Other research seeks to improve image interpretation through intelligent tools for object and environment recognition for the benefit of blind people [4]. Some studies focus on the personalization of the operation of mobile applications to facilitate people with special needs [5].

Some studies propose methodologies for using semantic technologies to support accessible learning [6,7]. Most consider models of accessible knowledge presentation through tutorials [8]. Some use semantic technologies to process learner response and progress at a given stage in the education of people with disabilities [9,10].

Examples of good practice are the initiatives of the UK government [11] for the accessibility of sites in the public sector of Great Britain, the German Bundesfachstelle Barrierefreiheit [12] in the field of communication and digital accessibility, and the Americans with Disabilities Act (ADA) compliance [13] for digital accessibility.

The authors of the present study are part of the team at the Institute of Mathematics and Informatics at the Bulgarian Academy of Sciences (IMI-BAS), which studied problems related to physical and digital accessibility for people with disabilities in Bulgaria from 2015 to 2024. As a result, a series of studies, developments, projects, trainings, manuals, surveys, games, reports, and publications related to this subject have been realized [14,15,16,17,18,19].

In their previous research on this topic, the team studied over 100 public sites (with a repeat after four years) and over 100 national sites, as well as the accessibility of 55 regional museums in Bulgaria. The findings of the team’s studies are not very encouraging. Most of the surveyed public sites in Bulgaria are still largely inaccessible and have a significant need to improve their digital accessibility for people with special needs. An accessible QR system with an audio guide has been developed for the purposes of the Regional Ethnographic Museum—Plovdiv.

The research project AB (Digital Accessibility for People with Special Needs: Methodology, Conceptual Models and Innovative Ecosystems) of IMI-BAS and the Institute of Robotics at BAS has as its main objectives to conduct in-depth research on the topic of digital accessibility and to develop a model of social-oriented accessibility ecosystem. One of the tasks is to create workable conceptual models for digital accessibility.

Research by the World Health Organization reflects the aging of the population and the increasing number [20] of people with disabilities. Currently, there are over 1.3 billion people with significant disabilities in the world, making up 16% of the world population, and in the EU, there are over 100 million people with disabilities [21].

The groups of people with physical and cognitive disabilities in the USA have the largest share—over 12% each [22], but these trends are also observed in other countries.

This research examines issues related to the accessibility of modern technology for people with special needs and the development of a socially oriented accessibility ecosystem. It explores how assistive digital technologies can help a user with a disability to access and use websites and applications and how this significantly improves their situation and makes them equal. Visually impaired users have been explored in several different roles, both as user and learner, as well as developer and educator. The second section explores recommendations, accessibility standards, and stages in building a website with ecosystem functionalities. The accessibility of the design, functionalities, structure, and content of the AB ecosystem are presented in the next two sections. The AB ecosystem model and its elements are described in more detail in the last part of the paper.

2. Guidelines, Accessibility Standards, and Stages in Building a Website with Ecosystem Functionalities

The modern, increasingly digitized environment in Bulgaria and around the world has led to changes in the work of software developers. Ensuring accessibility is gaining more importance and leading to new dimensions and additional requirements, standards, and recommendations for universal accessibility of software development. Software developers must constantly increase their awareness of the accessibility of websites and applications to different target groups of users, especially people with special needs. Bulgaria has introduced European requirements related to the accessibility of public sites, which obliges the developers of Bulgarian sites and applications to comply with the recommendations and guidelines for ensuring digital accessibility.

The Web Content Accessibility Guidelines (WCAGs) standard was developed by the World Wide Web Consortium (W3C). The WCAGs specify how to make websites and applications accessible to people with a wide variety of disabilities. The WCAGs 2.0, 2.1, and 2.2 updates cover a broad set of guidelines and success criteria for making web content more accessible to people with disabilities. The WCAGs 2.2 is the latest accessibility standard officially finalized by the W3C on 5 October 2023, with 9 new criteria that further improve web accessibility. The guidelines and success criteria are organized around four principles of accessibility (perceivable, operable, understandable, robust) [23] the observance of which makes technologies more accessible. If some of them are not fulfilled, people with disabilities will not be able to use the web.

W3C is in the process of developing a completely new version of WCAGs 3, which rethinks the approach to accessibility and its assessment [24].

The WCAG standard is partially or fully incorporated into various recommendations or laws related to website development. However, web developers also consider other practically important concepts such as UX/UI design, ergonomics, user-centered design, and usability. In the implementation of the functionalities, a distinction is made between usability and effective usability, and the determination of the effect is related to the degree of satisfaction of the visitors. Publications [25] on good practices for accessibility in web design related to the development of functionality, content, and design are useful in many cases. They are general recommendations that could also be used to improve accessibility or adapt to the specific requirements and goals of a site.

The issue of personalization of sites is an area of growing research interest [26] with strong applied importance because the adaptation of content and design should correspond to the specific needs of users. By successfully implementing the concept of web personalization, the performance and usability of websites can be significantly improved, and this can lead to a better user experience [27].

Recommendations and standards for accessibility for users with special needs to the developed digital environments and web systems lead to increased requirements in the development of ecosystems, as well. The web accessibility ecosystem model is compliant with the WCAGs.

The web ecosystem is a site of interconnected and communicating components, the functionalities of which cover various aspects of interaction with visitors, including access to various types of content, social networks, multimedia, training, feedback, news, and a collection of external links on the subject [28]. Usually, an ecosystem includes information from a large number of sources on a narrowly specialized topic, and the design, like web portals, has characteristics and peculiarities related to the construction of the structure and functionalities, including good systematization of keywords and categories, interactivity, comprehensiveness of a common theme, customization options, and more.

Related Work

The idea of the ecosystem is to support both ordinary users and people with professional interests in ICT. Numerous resources in English on digital accessibility exist, but for many, they are out of reach for reasons such as language barrier, low level of digital skills, etc. A project of the Inclusive Design Research Centre at OCAD University is considered in [29]. It proposes a theoretical strategy for digital accessibility, which is a broader view of regional or national level government regulations called “The Accessibility Ecosystem”. In the domain of inclusive education, the “Ecosystem of accessible digital content and tools” [30] presents a toolkit, tutorials, and implementations. Solutions for the implementation of information systems, practices, and tools for learning are presented in Ref. [31].

Table 1. A Comparative Analysis of Some Ecosystems.

Ecosystem	Similarities	Differences
ARCHES [2]	➢ Web-based ➢ Informational ➢ Customizable ➢ Based on standards ➢ Vocabulary ➢ Forums and social interaction ➢ Use of ontologies	➢ Community driven ➢ Data management ➢ Data discovery ➢ Visualization ➢ Project/task management ➢ Deployable ➢ Cultural heritage oriented
Center for Applied Special Technology [31]	➢ Web-based ➢ Informational ➢ Educational ➢ Online tools ➢ Resources ➢ Social interaction	➢ Oriented toward formal education
Accessible Digital Learning Portal [30]	➢ Web-based ➢ Raising awareness ➢ Informational ➢ Educational	➢ Oriented toward formal education ➢ No social interaction ➢ Tools are described only ➢ No customizations ➢ No multimedia ➢ No multilanguage support
The Accessibility Ecosystem Proposal [29]	➢ Digital accessibility oriented ➢ Legislative aspect	➢ Theoretical model ➢ Government oriented ➢ Not portal-like

presents a comparison between the four considered systems that have characteristics of an ecosystem and the capabilities of the AB ecosystem. It shows similarities and differences between the considered systems and the AB ecosystem.

One of the factors that have a determining influence on the design of the accessibility of ecosystems is the target groups of the users of the system. In terms of accessibility, users of the site could be organized into accessibility groups according to the types of disabilities or difficulties they experience when using the system.

Availability groups can be defined for:

• Visually impaired or blind users;
• Hearing-impaired or deaf users;
• Users with physical disabilities;
• Users with cognitive disabilities;
• Users with reading or learning difficulties.

Other factors related to user characteristics influencing the design of system accessibility are the level of knowledge, experience, and preferences of the user, as well as the user’s role (e.g., novice users, the elderly, people with disabilities, and visitors who are not well versed the language used on the site). Temporary limitations for visitors (momentary limitation) in terms of vision, hearing, movements, cognitive perceptions that are caused by a noisy/silent/distracting environment, devices used, medication, fatigue, driving, or other actions currently being performed are also permissible.

Building an accessible ecosystem begins with the systematization of all these rules and recommendations to which the work of web designers will be subject. If, among the goals of the ecosystem, it is assumed that the characteristics of the design differ for different groups of visitors, then the general rules and recommendations are also formulated according to the needs and expectations of each group.

Before actually building the accessibility ecosystem, it is necessary to consider and systematize the development steps. In relation to the goals set for the design of an accessible ecosystem, they must, in the first place, ensure accessibility, i.e., accessibility-first web design. At the same time, they should correspond to the accepted stages in the development of a site and to the peculiarities of the use of CMS. On the other hand, designers must comply with the recommendations of UX/UI design and SEO, which will meet the expectations and needs of all visitors, provide an accessible and positive user experience, and achieve website visibility. Figure 1 shows a diagram of the development stages of the accessibility ecosystem through CMS, where accessibility is given the highest priority.

• Project Description—Defining the aims and keywords, description of the characteristics of the target audience and the groups of visitors, including people with different disabilities and limitations, content strategy and resources, technologies that will be used, and development steps.
• Accessibility Requirements Research—Rules, standards, laws, practical advice and recommendations, comparative analysis of tools, themes, and plugins, and analysis of highly accessible sites.
• Planning the Content, Functionality, and Design—Systematization of good practices and important functionalities, creating accessibility documentation, planning content structure and headings, color scheme, typography, components, templates and navigation, user paths, and optimization planning.
• Development of Design and Functionalities—Implementing functionalities, installation and customization of plugins and themes, personalization of CSS styles, organization of text translations in theme and plugins, and security.
• Adding Content—Construction of information architecture and site map, posts and pages, alternative versions of the content (texts, subtitles, descriptions), and content protection.
• Testing the Logical Sequence of Elements on a Page—Device (screen readers, keyboard controls, etc.) usability and accessibility, multimedia, link colors (contrast, readability, color blindness), user experience security test. Automated testing using specialized analysis tools and manual user testing with the participation of the various focus groups are conducted. After each test, there is an analysis of the test results, a correction in accessibility strategy and functionality, and retesting.
• Maintenance and Updating—Accessibility and new practices and standards, design, functionalities, and content, with an accessibility rating of the new elements’ efficiency and optimization analysis of information from user feedback.

3. Accessibility of Design and Functionalities of the AB Ecosystem

The main goal of the proposed ecosystem is to increase awareness of more people through a complex of information and tools.

General recommendations to ecosystem accessibility designers can be defined, stemming both from general site accessibility requirements and related to ecosystem features and functionalities.

General recommendations for accessibility of the AB ecosystem:

• Any non-text content should be accompanied by a text alternative as a description of that content. This applies to elements such as images, icons, videos, and picture buttons, and the added text must be short, understandable, sufficiently meaningful, and maximally descriptive in relation to non-textual content.
• Large platforms that cover different aspects of a given issue often contain multiple media elements. It is necessary to add subtitles to audio and video information and options for visitors to choose between media types, subtitles, and text, further describing important visual details of the media content.
• Media alternatives should be clearly marked as such to make it easier for visitors and programs to read content.
• Color contrast in design should help distinguish certain web elements, with a more significant role for non-visually impaired visitors, and, thus, generally increase the usability of web content. At the same time, people who have visual impairments should also have access to this distinction, but not on the basis of color.
• Research color schemes and their impact, as well as the requirements for sufficient color contrast of textual elements, and increase their importance in the design of the graphic elements of an ecosystem. It is necessary to build a common model of such elements and an alternative mechanism for presenting text for people with different types and degrees of visual impairment.
• A mandatory element for a successful site is the functionality of choosing the font size of the text. This is achieved with text scaling tools and through design that adapts to the different sizes of visitors’ devices (Responsive Web Design) and is embedded in most web design techniques and programs. This should not compromise the quality of web content or user experience. The horizontal scroller and the small line spacing in longer text paragraphs have a strong negative effect on it.
• It is accepted and expected by users to have images added to any textual information for illustrative purposes. Very often, they do not bring any additional information to the visitors but only enhance the visual experience, and for this reason, their removal would not be justified. They need to be marked as decorative in order to be counted by assistive technologies.
• All functionalities should provide control of the content from the keyboard. When using reading programs, it is recommended to achieve a high level of efficiency and, particularly, a good user experience for blind visitors.
• An important principle in UX/UI design is the handling of user errors. Errors should be prevented, expected, clearly marked, and given the opportunity to refuse or correct the wrong action. Descriptive error texts can be contextual or positioned at the top of the content and should make it as easy as possible for the user to understand the problem and act. Sections with tips or frequently asked questions also help the user.
• Compliance with the four principles of the WCAGs and the relevant guidelines and criteria for success of the standard.

Recent statistical studies show an increase in the number of sites that are created and administered using content management systems [32,33]. The use of such software shortens the work of web developers and makes it possible to pay more attention to the characteristics of future site visitors and their needs and expectations. An important design stage is the choice of external layout, which begins here with defining a WordPress theme with its available elements, layout, settings, and functionalities. When creating an accessibility ecosystem, however, the accessibility of the chosen topic is set as the leading requirement, followed by providing the necessary functionalities in accordance with the specific goals set for the platform and facilitating the creation of the above-mentioned elements and functionalities.

Most of the available WordPress themes offer at least the minimum level of accessibility, marked with an “accessibility-ready” tag, but when a learning-oriented criterion is added, the list shrinks significantly. The accessibility-ready level is defined in relation to the WCAG rules, but here, they are adapted according to the specifics of WordPress. Regardless of this label, each theme must meet a smaller list of accessibility requirements related to easy keyboard navigation and clearly distinguishable in-text links. The accessibility-ready label is optional, but web developers are encouraged by WordPress to meet and even exceed its requirements. Available requirements relate to heading structuring, contrasting color schemes, and the inclusion of links, images, multimedia, and ARIA attributes. However, adjusting text size and using the title attribute remain only recommended, and other accessible design requirements are not even included as recommended. For these reasons, theme analysis, choosing a theme with accessibility features, and adjusting and changing play an important role in developing an accessible site.

Table 2. A Comparative Analysis of Some WordPress Themes Suitable for an Accessible System.

Topic	Duration	Updates	Accessibility Level	Testing (Results)	Number and Rating of Users	Other Features
Reykjavik	6 years	Frequent	WCAGs 2.0 level AA	Structured titles, keyboard navigation, page descriptions, localization-ready	Small, 5/5	Elegant design, fast loading, SEO, color contrast, sidebar, templates
Twenty Twenty-Four	New	Frequent	Accessibility-ready	Presence of incorrect formatting of links in text, unavailable models and contrasts	Very large, 4/5	Multiple settings, templates, mobile friendly, SEO
Maisha Lite	5 years	Rare	Accessibility-ready	Color and contrast settings in the paid version	Very small, 4.5/5	Adapted for mobile devices, templates, settings, microformats
Koji	5 years	Frequent	Accessibility-ready	Sidebar, translation-ready, advanced settings	Small, 5/5	Minimalistic design; functionalities are suitable for a blog
Period	7 years	Frequent	Accessibility-ready	Adapted for mobile devices of different types, translation-ready	Small, 4.97/5	Contrast levels, keyboard control, minimalistic design, sidebars

lists several WordPress themes that were analyzed and benchmarked using various tools. There are other themes available that pay more attention to accessibility on the one hand and features such as fast loading, efficiency, responsive design, and available customizations on the other. The disadvantages of many of the themes offered in the context of the accessibility platform goals are infrequent updates, the special focus on an e-commerce application, and the fact that some of the important features and customizations of the themes are only available in the advanced versions.

The analysis of these themes led to the selection of the Reykjavik theme [34] based on the high level of accessibility, the very good results of the automated and human tests performed, and the wide range of functionalities and customizations included in it.

The next stage in the design of the accessibility ecosystem is the analysis of plugins that extend functionalities and improve accessibility. The main goal here is to analyze the existing elements to increase the level of accessibility and the possibility of adding them to WordPress. This can be achieved by adding functionality to the site or by adding functionality to the WordPress content management system used. For example, some of the following functionalities can be added:

• A site settings panel designed for visually impaired visitors that can change the font size, increase the contrast of colors used, highlight links, replace text fonts with readable font, switch from a dark to light color scheme, convert color images in black and white (monochrome), additional marking of links or titles, switching to a mode for viewing the site without applied styles or mode with text only, mode without animations, text alignment settings, line and letter spacing, color and cursor size, screen ruler and focus mode (reading mask) or reading mode, control over the design and size of icons and buttons, etc.
• Tools to make it easier for the web designer to create an accessible site that can remove unlabeled links, check for added alt text on images, option to turn off title attribute for links, add role attribute to links, create accessibility compliant forms, storing and reusing color combinations, accessible texts and components, accessibility monitoring, etc.

The first group of plugins is primarily aimed at the visually impaired, but there are also plugins that make it easy to add content tailored to the needs of people with dyslexia, physical disabilities, reading difficulties, and more. Accessibility for all groups of visitors is additionally achieved by selecting, enriching, and structuring the content of a site.

When choosing an accessibility plugin, in addition to functionality, compatibility with the already selected WordPress version and theme, as well as compatibility with other installed plugins (for example, for a multilingual site), frequent updates, a high number of active installations and user opinions, and a detailed description of the development are important. Plugin creators pay attention to compatibility with other programs, but the task of web developers is to analyze the possibilities of alternative options for choosing plugins, including functionalities, compatibility, and customizations, and make a choice according to the goals of the ecosystem and the organization of their development.

For the development of the accessibility ecosystem, several of the most popular accessibility extensions were analyzed and evaluated, including WP Accessibility Helper (WAH), Accessibility Enabler, All in One Accessibility, One Click Accessibility, Simple Accessibility Button, Accessibility Lite, Zeno Font Resizer, and Simple Font Resizer. Some of them implement few accessibility functionalities (e.g., only changing the font size) and few customization options, which in a large ecosystem means more additional CSS code and managing several plugins at the same time. Others focus on comprehensiveness in terms of accessibility and SEO best practices and, thus, achieve the comfort and satisfaction of web developers. Using an extension does not guarantee that the result will be a fully accessible site, but each of them helps to achieve such a result. As one of the extensions offering a large set of functionalities for visitors with disabilities and tools for web developers, and at the same time frequently updated and highly appreciated by designers, WP Accessibility Helper (WAH) was evaluated and selected for the development of the AB ecosystem.

Regarding the design of an accessible site with WordPress, it is important to mention that the established community of web developers actively shares problems that they encounter in their work in specialized forums [35]. Some of these issues are related to the accessibility of the sites, and sharing them is helpful for aspiring designers.

4. Accessibility of Structure and Content of the AB Ecosystem

Ecosystem structuring is essential to orient users in a large system with diverse types of resources. This is especially important for visitors with cognitive disabilities.

The following key recommendations were identified in the AB ecosystem:

• The arrangement of the content of the pages should correspond as much as possible to its markup in the code of the web pages, implemented through sections, subsections, headings, and nested subheadings.
• The arrangement should also be consistent with the priority of the elements in a web page such that elements related to the management of the available functionalities are at the highest position. An important UX principle is visual hierarchy, determining the arrangement of elements in the flow of content according to their importance.
• Web pages with longer content should start with the structured content of links to sections and subsections. This would make it easier for all visitors to find what they are looking for.
• Functionalities to hide and show content elements would give a comprehensive view of the text structure but could also save time when reading with a program or keyboard control.
• The structuring of the web content also refers to the precisely chosen names of titles and subtitles, link labels, and menus. They must, above all, be clear and concise, comprehensible, and unique to ensure easy orientation of all visitors and to avoid confusion and dissatisfaction from a wrong choice and, accordingly, a bad user impression. Adding additional short explanations in the form of tooltips where appropriate will guide those users who are unsure of understanding the short titles and give them additional confidence in their own ability to control their access to content.
• Accompanying the determination of the structure of the content and its distribution in individual web pages is the planning of the navigation and its adaptation to the different preferences and needs of the visitors. In some cases, it is advisable to duplicate links and paths to reach a given content. Less commonly used but faster ways to identify the information sought are building and maintaining an ecosystem map, quick links in the footer, and a section in a post with a list of contextually related pages.
• Good structuring of content, combined with more simply presented information, can contribute to easier understanding and uptake of information by all types of users. Facilitations are glossaries added as links or tooltips, summarized content as a link to the full text, definition of abbreviations, infographics, and versions of the content using simplified language (for beginners, people with learning difficulties, or people with insufficient knowledge of the language on the site).
• Avoiding long paragraphs and long sentences will lead to a better understanding of the text by people with cognitive difficulties and, thus, to a higher level of satisfaction for this group of visitors.

Building the information structure is a complex and lengthy process that also depends on the scope of the content. In the development of the AB ecosystem, various goals have been set, such as site accessibility research and accessibility education, systematization of up-to-date information and digital resources on the topic of accessibility, etc. The hierarchy of content must meet all the recommendations systematized above, be balanced and user-friendly for visitors, and navigation should offer quick and unmistakable orientation. Figure 2 presents a diagram of the modules of the ecosystem, which presents the content in a website tree structure.

The importance of each module and its interrelationships with other modules are important, and therefore, all components and relationships in the system should be planned at the site design stage, even if they are not built at the same time. The tree model is the most common and is built on the basis of the priorities of the information units. For the content in the training module, it is appropriate to apply a linear structure, while the structure of a Blog module with added taxonomy is more of a network with many links between posts. This ensures access to the information sought with fewer clicks and users follow their own sequence of viewed pages, called a personalized navigation path. Visitors have the opportunity to familiarize themselves with the structure of the site in the so-called HTML structure of the site (site map), and for the convenience and correct indexing of the site by search engines, an XML site map is implemented.

The training module includes courses and lessons from different areas, such as accessibility lessons, programming, and educational games, which were built with different user groups in mind—both learners and trainers. The Applications module includes Accessible Cultural Heritage, Accessible Media, Social Robotics, and Famous People with Disabilities.

The team studied famous people with disabilities from various fields, their achievements, and the role of assistive technologies in obtaining opportunities for career and personal growth. As a result of the research in the developing AB ecosystem, a special module on famous people and their achievements was added in order to obtain historical information and knowledge on this topic. Unstructured data are stored in digital storage using cloud technologies. The information in the archives is grouped by category and can be continuously updated.

The ecosystem provides a variety of opportunities for interaction with users, such as links to social networks and a discussion forum, which are built according to the rules of UI design, function as feedback for developers, and strengthen the social role of the ecosystem. The archive module, including scientific publications, laws, and applicable accessibility rules, also contributes to the cultural–social role, relevance, and comprehensiveness. In separate modules, the tools for checking accessibility, systematized according to the objectives of the check, and the tools supporting the provision of accessibility are analyzed.

Related to the design of the site structure is the strategy for internal links, which defines the logical connections between the parts of the content and provides convenient navigation for each group of visitors.

Semantic knowledge about accessibility includes various concepts, relationships, rules, constraints, individuals, and facts. The knowledge structure model for people with special needs was investigated and, as a result, a conceptual model of semantic accessibility knowledge was developed, which includes ontologies, taxonomies, and knowledge bases. This knowledge supports the access of people with special needs to digital resources (Figure 3). It improves the personalization of the user experience according to their specific needs and requirements. It includes knowledge related to accessibility in the field of information technology and partly in the humanities and social sciences. The selection of core concepts is based on real statements, situations, and reality. The description of facts, objects and situations with which individual objects (individuals) are connected is conducted in the process of studying the objects.

Separate ontological substructures are structured for the subject area, including Ontology of Accessibility, Ontology of Accessibility of Digital Objects, Ontology of Accessibility Requirements, Ontology for Accessibility to Learning Materials and Learning Processes, and Taxonomy of Accessibility. More about the structure and organization of the ontology can be found in [36]. The ontology is developed using custom collaborative ontology engineering methodology. The process consists of a formal definition of the tasks required for design and consultation with different professionals (accessibility experts, education specialists, IT professionals, etc.) participating in the development.

5. AB Ecosystem Model and Element Realization

In creating the AB ecosystem model and content strategy, W3C’s WCAG standards and recommendations related to web design in general and web accessibility in particular as a topic and goal of the ecosystem were examined.

The creation of content and the selection of the placement of elements on each page of the site are subject to the requirements of familiarity (by adhering to established patterns), usability (by providing alternatives), readability (by careful selection and optimization of texts and descriptions), hierarchy (through sections and subheadings), contrast (marking important elements with or without color), orderliness (through lists and sections), quick navigation (through precise and short link labels). Figure 4 shows a diagram of the arrangement of the elements, which ensures balance, proportionality, and consistency.

Navigation in an ecosystem has a leading role in the planning stage, as it is related to the convenience of visitors with a large volume of content available. On the other hand, accessibility requires a simplified model and maximum link descriptions. Figure 5 presents the main menu with short link labels and an optimized thematic structure.

The navigation model is completed by the footer with the main quick access links and the elements in the sidebar, including lists of recent posts and comments, archives, and taxonomy. The Tag Cloud (see Figure 6) also provides a display of the number of posts with the specified tag to ensure accessibility for screen readers.

An ecosystem map has been built that presents the main modules in a structured list of links. Alternative versions of this map are given in two formats—a scheme (Figure 7) improving the orientation of visitors through the visual representation of the structure and a map with descriptive elements of the modules in it. Blind visitors would not be able to use the graphic representation in a diagram, but it would facilitate visitors without visual impairments. The map with added descriptions will improve navigation for visitors with cognitive disabilities who find it more difficult to navigate a longer and more structured list.

Important parts of the construction and implementation of the model are the customizations of the selected WordPress theme and the added plugins. The theme allows customization of page templates and widgets, custom styles when editing a post, and sidebar management. Sidebar widget customization to display recent posts in the ecosystem is performed through the standard WordPress capabilities, through the additional settings embedded in the theme, or through an additional CSS class for the selected block (Figure 8).

To create the Bulgarian version of the content of the ecosystem, a multilingual Polylang plugin with additional settings is needed. The chosen topic is “localization ready”, which ensures a faster translation of its elements for the Bulgarian version of the ecosystem. Of particular importance is the customization of the WP Accessibility Helper (WAH) accessibility settings panel, which provides a quick orientation to users of any target group through simplicity, short, understandable labels, a wide selection of settings, structure, and order.

The issue of content personalization according to the visitor’s belonging to a given accessibility group with the corresponding needs and expectations is crucial. The most common accessibility personalization model is the following:

• The content and structure are in a format that is tailored to most groups of visitors; for example, the texts are written clearly and comprehensibly, a structure is introduced in sections with headings and sub-headings, a color scheme is selected with sufficient contrast, there are descriptions of the multimedia elements, and they are visible to the reader programs, added subtitles to the sound and video files, etc. According to their needs, visitors have a choice of what and how to get acquainted; for example, watch and listen to the video, watch and read the subtitles, hear the sound and descriptions of the video, and get acquainted with the additional explanatory information.
• The design allows individual settings according to the wishes of each visitor—readable font, content scale, title and link marking, color settings, mute, focus, cursor settings, etc.

The AB ecosystem aims to achieve a high degree of customization, with the added accessibility plugin WP Accessibility Helper providing the second of these ways via an accessibility panel (see Figure 9), and the intended structure of modules, menu, and elements aim to achieve of accessibility and in the first way mentioned above.

An alternative solution for personalization is the implementation of separate profiles for each group of visitors. Then, at the start of their visit, each visitor can select an accessibility group profile—blind, visually impaired, cognitively impaired, etc. The design of the web pages will then be tailored to the group’s needs and provide maximum user experience.

The accessibility ecosystem model also addresses the issue of site security. The solutions are based on the project team’s previous research related to software technologies and their applications in error-correcting codes.

6. Conclusions

The modern, increasingly digitized environment in Bulgaria and around the world has increased the role and relevance of accessibility for everyone, both for users of digital sites and applications and for software developers. Ensuring universal accessibility is gaining more importance and leads to new, positive changes and trends in the professional and personal development of people with disabilities. Modern sites meet at least some accessibility requirements, but accessibility is increasingly a high priority for web developers. If the design of a site is tailored to different groups of visitors, then its accessibility would be more sustainable, and therefore, future corrective actions would be required less often. Web designers are assisted by numerous online and scholarly publications that address accessibility design issues, for example [37]. Most of the popular articles give only general guidelines and a list of a few individual tips without detailing the initial analysis and the long testing stage, and the main goal is to achieve a high level of accessibility in a short time. In this publication, the steps of building an ecosystem and the requirements for them were systematized and presented in depth, with the main goal of a high degree of accessibility.

Discussion of Limitations and Future Research

The main limitation of the ecosystem is that currently, it is based mainly on research on the needs of people with disabilities in Bulgaria. This is caused by the essence of the scientific project within which the system is created. Despite this fact, the system is projected in a way that it can be easily extended and generalized.

In future experiments and improvements, the content will be enriched with more materials related to international case studies, and the ecosystem interface will be translated into different languages.

Other ideas for further developing the ecosystem include enriching the training module and designing a new accessibility evaluation module.

An artificial intelligence module is planned for the AB ecosystem, providing visitors with chatbot functionality. For its creation, it is necessary to analyze existing WordPress plugins with their characteristics and parameters, advantages, compatibility, and settings from the point of view of accessibility. It will improve user interface customization and increase satisfaction and user experience.