Table 3.

Barriers and facilitation measures categorized by the ‘understandable’ foundational principle of Web accessibility.

Barrier	Facilitation measure
Information overload [34]	Ensure information is organized well and avoids distracting designa.
Poor organization and presentation [34]	Ensure information is organized well and avoids distracting designa.
Excessive advertisements [34]	Ensure information is organized well and avoids distracting designa.
Confusing menu options [34]	Avoid complicated language and ensure menu options and links are easy to understanda.
Complicated language [34]	Avoid complicated language and ensure menu options and links are easy to understanda.
Complex purchasing process [34]	Avoid complicated language and ensure menu options and links are easy to understanda.
Distracting design [34]	Ensure information is organized well and avoids distracting designa.
Use of abstract reasoning [38]	Present text at a low reading levelb.
Difficulty comprehending text [33]	Present text in large font and language below a fifth-grade reading levelb.
Difficulty understanding abbreviations [30]	Remove abbreviationsb.
Difficulty understanding long words [30]	Reduce textb.
Too lengthy text [30]	Simplify wording to fourth-grade levelb.
Overabundance of information [41]
Unwanted movements or flickering [36]
Cluttered design [36]
Lack of logic and consequence in concept and design [36]	Provide resources in video and audio formata [35]. Use a modular and hierarchical approach when presenting informationa [35]. Present important information firsta [35]. Use large navigation buttonsa [32]. Provide explicit labels that use longer concrete phrases to describe contenta [32]. Explicit instructions on how to use the websitea [32]. Provide text at fifth-grade reading levela [32]. Provide instructions on how to navigate programs and websitesa [42]. Use a simple design with pages that are pleasing to the eye and easy to reada [31]. Provide category headings that clearly identify what information is underneatha [31]. Use menus with options that are ordered in a meaningful way and/or have an evident hierarchya [31]. Give a clear identity to the homepagea [31]. Provide a homepage with just the right amount of information (graphics, text, links) to make the page understandable without overwhelming the usera [31]. Use language that the user can identify witha [31]. Meaningfully group of informationa [31]. Use graphics that are purposeful to the websitea [31]. Comprehensively list hyperlinks surrounding a given topicb [37]. Include minimal amount of content on pagesb [37]. Single topic of interest: group hyperlinks and topics in one area of the screenb [37]. List hyperlinks for a given topic together in a single columnb [37]. Use an ample number of images and visual aidsb [30]. Provide content users can identify with (eg, case stories, worked examples, and success stories)b [40].
	Use a flat hierarchyb [38]. Provide explicit labelingb [38]. Use lower-level modules (eg, code and data to implement a specific functionality)b [38]. Use familiar phrasingb [38]. Guideline 3.1: Make text content readable and understandablec [23]. Guideline 3.2: Make Web pages appear and operate in predictable waysc [23]. Guideline 3.3: Help users avoid and correct mistakesc [23]. Guideline 7: Observe operating environment conventions for the user agent user interface, documentation, input configurations, and installationc [44]. Guideline 12: Ensure that the user can learn about software features that benefit accessibility from the documentation. Ensure that the documentation is accessiblec [44]. Guideline 2: Ensure that users have access to all content, notably conditional content that may have been provided to meet the requirements of the Web Content Accessibility Guidelines 1.0c [44]. Guideline 3: Ensure that the user may turn off rendering of content (eg, audio, video, scripts) that may reduce accessibility by obscuring other content or disorienting the userc [44]. Guideline 4: Ensure that the user can select preferred styles (eg, colors, the size of rendered text, and synthesized speech characteristics) from choices offered by the user agent. Allow the user to override author-specified and user agent default stylesc [44]. Guideline 5: Integrate accessibility solutions into the overall “look and feel”c [43]. Guideline 6: Promote accessibility in help and documentationc [43]. Guideline 4: Provide ways of checking and correcting inaccessible contentc [43]. Guideline 1: Support accessible authoring practicesc [43]. Guideline 7: Ensure that the authoring tool is accessible to authors with disabilitiesc [43]. Guideline 3: Support the creation of accessible contentc [43]. Guideline 2: Generate standard markupc [43].

^aFacilitation measure derived from expert opinion of researcher(s) conducting a study.

^bFacilitation measure derived from empirical evidence.