Use markup that aids pronunciation or interpretation of abbreviated or foreign text.
When content developers mark up natural language changes in a document, speech synthesizers and braille devices can automatically switch to the new language, making a document more accessible to multilingual users. Developers should identify the predominate language of a document in the markup. Abbreviations and acronyms should have expansions as well for easier understanding. Natural markup language also helps search engines in finding key words and web pages in the desired language. The document also states that just the overall use of natural language markup will help web users and those with disabilities.
Checkpoints:
4.1 Clearly identify changes in the natural language of a document's text and any text equivalents
4.2 Specify the expansion of each abbreviation or acronym in a document where it first occurs. For example, in HTML, use the "title" attribute of the ABBR and ACRONYM elements. Providing the expansion in the main body of the document also helps document usability.
4.3 Be sure to identify the primary natural language of a document. For example, in HTML set the "lang" attribute on the HTML element. In XML, use "xml:lang". Server operators should configure servers to take advantage of HTTP content negotiation mechanisms so that clients can automatically retrieve documents of the preferred language.
I think it is important to provide aids for pronunciation of foreign texts and abbreviations. But it is more important to provide proper markup for individuals that rely on text to voice software to read their web pages to them so that they can understand the webpage in their language. If the language of the document is placed in the markup, search engines can find web pages related to the users language. To see the detailed Guideline information follow this link.