Справка LibreOffice 24.8
Assigns a text and an alt text to the selected object. These texts are available as alternative tags in your document for use by accessibility tools. They are also available as tags for images when you export the document.
Enter a short description of the essential details of the selected object for a person who cannot see the object. This text is available for use by assistive technologies.
Enter a longer description of the object, especially if the object is too complex or contains too much detail to be described adequately with the short Use . to add additional information to the short description found in . This text is available for use by assistive technologies.
Marks the item as purely decorative, not part of the document content, and ignorable by assistive technologies.