According to the WCAG 2.1 guidelines, there are three levels of conformance that a website can meet the needs of different groups and different situations: A (Lowest), AA (Mid-range), and AAA (Highest). Single-A can be considered as the minimum level of requirement for all websites, and AAA can be viewed as the ideal standard level of accessibility for all websites, but there are some issues to reach AAA such as budget issues. As our guidelines focus on reducing help-seeking situations that BVI users encounter in the DL environment, Table1, 2 and 3 present three levels of conformance recommendation to address different types of help-seeking situations based on our user studies (frequency of situations BVI users encountered and levels of functions ranging from basic to advanced they need to use in interacting with DLs) and existing research: A (Lowest), AA (Mid-range), and AAA (Highest).
Table 1. Level A
| Symbol | HSS | Guideline |
| ACC1 | Difficulty directly accessing files |
1. Ensure that linked files and attachments are accessible and directly opened. 2. Ensure that relevant information about options to access files is presented to users. |
| ACC2/COM3 | Difficulty accessing/comprehending images |
1. Provide a meaningful description for each image. 2. Provide instructions on ways to access image descriptions through mobile assistive technologies. 3. Ensure that file formats of image items are compatible for screen reader access. |
| ACC5 | Difficulty accessing expandable/collapsed content |
1. Ensure that the DL enables screen readers to follow the executed actions. 2. Ensure all interactive elements, like buttons and links, are clearly labeled with meaningful text. |
| RED1 | Difficulty recognizing the availability of search results | 1. Ensure that a change in DL status is accompanied by instant notification. |
| EXE1 | Difficulty clearing a search box | 1. Ensure that the process of clearing a search query from the search box is efficient and effective. |
| EXE2 | Difficulty exiting an open item |
1. Ensure that all features are labeled clearly and meaningfully. 2. Ensure that the close or back button consistently appears on the opened item. |
| FIL1 | Difficulty finding/locating an icon-based search feature |
1. Ensure that an icon-based search feature is easily discoverable and recognizable with an appropriate label. 2. Ensure that the access to an icon-based search feature is simple. |
| EVA1 | Difficulty assessing relevance of a collection or an item |
1. Ensure the associations between the search result/items and the query terms are presented. 2. Provide a meaningful description for each item in the search results. |
| COM1 | Difficulty understanding a digital library structure |
1. Maintain a simple and logical structure 2. Maintain a simple and clear layout 3. Ensure that structural elements are understandable. |
| NAV5 | Difficulty navigating to a search result section |
1. Provide clear and descriptive design elements that support mobile navigation to a search result section. 2. Ensure a simplified path to the search results. |
| INT1 | Difficulty interacting with multi-layered windows |
1. Ensure that screen reader focus is confined within an active pop-up window until an exit action is detected. 2. Provide feedback when the screen reader focus moves between windows, informing users of context changes. |
| FIL3/HEP1 | Difficulty finding/locating/using mobile-specific help information |
1. Ensure that mobile DL related help information is available. 2. Ensure that mobile screen reader related help information is present. 3. Ensure that mobile-specific help information provided by voice commands is obtainable. |
Table 2. Level AA
| Symbol | HSS | Guideline |
| ACC3/COM4 | Difficulty accessing/comprehending graphs |
1. Provide a meaningful description and label of each graph. 2. Ensure each interactive graph is accessible and its function is understandable. 3. Ensure each interactive graph has a meaningful explanation of its dynamics. |
| ACC4 | Difficulty accessing collection items |
1. Provide easy access to collection items. 2. Provide concise collection descriptions (e.g., content, scope, and organization). |
| RED2 | Difficulty distinguishing collection titles from thumbnails |
1. Ensure that collection titles and label/alt text for thumbnails are easily differentiated. 2. Ensure that collection titles and alt text of thumbnails present different levels of collection description. |
| EXE3 | Difficulty returning to a previous page | 1. Ensure clear and descriptive features that support returning to a previous location or page. |
| FIL2/RED3 | Difficulty finding/locating/distinguishing search features at different levels |
1. Ensure that search features at different levels are placed in appropriate/relevant locations. 2. Ensure the labels for search features are intuitive and specify different levels of searches. |
| NAV2 | Difficulty navigating paginated sections |
1. Ensure that the structure of the paginated section is clearly presented. 2. Ensure that labels for active elements indicate their content meaningfully. 3. Ensure that the navigation within different pages of the section and items of the page is efficient. |
| NAV3 | Difficulty navigating through search results |
1. Ensure that going through search results list is efficient.
|
| NAV4 | Difficulty navigating within an item |
1. Ensure efficient and effective navigation to a specific section within an item. 2. Provide alternative mechanisms to navigate through tabulated content. 3. Provide an overview of lengthy and complicated items with links to the sections. |
Table 3. Level AAA
| Symbol | HSS | Guideline |
| ACC6 | Difficulty accessing a query suggestion |
1. Ensure feedback is in place to notify users of the availability of auto suggestions. 2. Ensure easy access to query term suggestions to assist users in completing their search queries. |
| RED4 | Difficulty recognizing authorized features |
1. Ensure the restriction of features is easily recognizable. 2. Provide clear instructions on how to access authorized features.
|
| COM2/NAV1 | Difficulty understanding/navigating the search filtering structure |
1. Ensure that filtering options are organized by categories in a logical order. 2. Ensure that filtering option categories can be flexibly and concisely presented. 3. Ensure a specific filter option can be reached efficiently. |
| USE1 | Difficulty using screen readers and voice activated commands |
1. Ensure that the design of DLs is compatible with assistive technologies.
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