1996年、Web Accessibility Initiative（WAI）が設立され、その3年後に最初のウェブアクセシビリティに関するガイドラインであるWeb Content Accessibility Guidelines（WCAG）1.0が発表された。WCAGは、ウェブアクセシビリティの4原則として、全てのユーザーにとって、知覚可能であること、容易に操作できること、容易に理解できること、技術的に堅固であることを定めている。
紹介された文献（のPDF）ではWeb Contentとして3ページ弱の内容が割かれてますけれども、これを1段落にまとめるにしても、WCAG 1.0が（WCAG 2.0の）4つの原則を持っているようにまとめてしまっている状態なわけであり。このあたりはWCAG（の歴史）にある程度触れていればおかしなことに気付くと思われますが、予備知識なしには難しいものなのか…もしれない2。もうWCAG 1.0は廃止されましたしね…。
ちなみに原文はCC BY-NC-NDということもあり、参考までにWeb Contentのセクションをそのままはっ付けておきます。機械翻訳するなりしてお楽しみください。
In 1996, several members of the World Wide Web Consortium (W3C) turned their attention towards web accessibility, ultimately founding the Web Accessibility Initiative (WAI) (Dardailler, 2009). Three years later, the first set of web content accessibility guidelines was released as WCAG 1.0 (Chisholm, Vanderheiden, & Jacobs, 1999). In 1998, the Rehabilitation Act was amended by Congress to include Sect. 508, which required federal agencies to make electronic and information services accessible to people with disabilities (GSA, 2018). Today, library websites serve as a critical point of access to library information and services for disabled and neurodivergent individuals and communities.
WCAG 2.0 was released on December 11, 2008. These updated guidelines were designed to “make content accessible to a wider range of people with disabilities, including blindness and low vision, deafness and hearing loss, learning disabilities, cognitive limitations, limited movement, speech disabilities, photosensitivity and combinations of these” (Caldwell et al., 2008). The WCAG 2.0 effort included a large-scale reimagination of the former 1.0 guidelines, including the addition of “success criteria,” which were added to simplify the testing process. The release of WCAG 2.0 also saw the introduction of three conformance levels—A, AA, AAA— where Level A represents “the minimum level of conformance” and Level AAA represents conformance with all success criteria (W3C, 2016).
Furthermore, WCAG provides four principles for web accessibility. The first principle, perceivability, means that the content and interface of a website must be perceivable by all users. The second principle, operability, means that the elements of the user interface must be easily operable by all users. The third principle, understandability, means that the content and controls of the website must be easily understood by all users. The final principle is that of robustness: content must be technically robust such that it can be perceived by, operated on, and understood by users with current and future technologies, including assistive technologies. Currently, in the United States, laws requiring web accessibility in a growing number of public accommodations, institutions, and agencies (such as public libraries, colleges, and universities) are harmonized with WCAG 2.0 conformance Level AA (Kuykendall, 2017).
Most of the research on library accessibility is focused on accessible web content, particularly on academic library sites. Some research, such as that elaborated in Comeaux and Schmetzke (2013), shows that even while libraries intend to make their web content accessible to patrons with disabilities, many still struggle to reach WCAG guidelines. Comeaux and Schmetzke evaluated 56 academic library websites for two years in North America and found around 60% of the libraries’ web pages complied with WCAG 1.0 guidelines. Similarly, Khawaja (2022) recently evaluated the accessibility of a total of 120 public library website URLs in the United States using an evaluation tool for testing WCAG 2.1 compliance. Their results showed that public library websites overwhelmingly failed to meet the accessibility standards required by law in Sect. 508 of the Rehabilitation Act.
Mulliken (2019) interviewed blind academic library users to understand the barriers they experienced when accessing academic library websites using screen readers. They found that although participants found the library website materials accessible, they could not easily navigate the web pages due to a steep learning curve, which prevented them from being able to successfully use the website. A study by Liu, Bielefeld, and McKay (2017) evaluated urban public library website homepages and uncovered a variety of issues across 219 library websites. The most common errors were websites missing alternative text and form labels. In another study, Graves and German (2018) found that few accessible pages provided instructions for accessing library programs and services for those with accommodation needs. Likewise, Vaughan and Warlick (2020) examined a sample of websites from 40 four-year academic institutions and evaluated them based on the presence of 12 types of content, which included things like an accessibility statement, accessibility information, and disability services. They found that fewer than half of the web pages included seven of these 12 content types, and that the majority of the academic library web pages did not contain a single accessible web page at all. Clearly then, despite the array of research published on library web accessibility, accessibility issues continue to be commonly found on library web pages (Brunskill, et al., 2021; Yang et al., 2020).