Document title must not be blank.
Page 1 WCAG2 A F25
For HTML pages change the TITLE tag. For Office documents and PDF documents produced from Office, fill in the Title in Document Properties before saving as PDF.
Use the LANG attribute to identify the language of the page.
Page 1 WCAG2 A 3.1.1
In HTML add a LANG attribute to the HTML tag, and in PDF set the language using Document Properties in Acrobat. This allows screen readers to pronounce words correctly.
PDFs must be tagged to be accessible by screen readers.
Enable the "Document structure tags" option in Word, or the "Tagged PDF" option in OpenOffice when exporting, or use the "Make Accessible" plug-in for Adobe Acrobat.