Leave Name as the Value Type.Approximately 253 million people worldwide have a visual impairment, according to the World Health Organization, which means making your website accessible to this unique population of internet users should be a priority. In the Add Key and Value dialog, enter Placement in the Key field, and Block in the Value field. Select “/Attribute Object # >” and click the New Item button.Ħ. In the Attributes dialog, if there is not a “/Attribute Object # >” item, click the New Item button.ĥ. On the Tag tab of the Object Properties dialog, click the Edit Attribute Objects button.Ĥ. In the Acrobat Pro Tags pane, right click the Formula tag.ģ.

Otherwise some assistive technologies are not able to present it correctly. If it is used as a block level element, the attribute “Placement: Block” is required.

The Formula tag is an inline level element.

Nest a tag in the Formula tag that has a text alternative in an Actual Text attribute.

…according to Ted Page of Accessible Digital Documents, if you do so, the content may not be read by some earlier versions of the NVDA screen reader, with or without an ALT attribute. “Because speech software may handle Formula tags differently from normal text, it may be necessary to add a description using alternate text.” You have to remember that the screen reader user is listening to the equation, so its ALT text description would be set to:ĪLT=”m equals begin fraction m sub 0 over begin square root 1 minus begin fraction v sup 2 over c sup 2 end fraction end square root end fraction”

Sometimes just complying with basic standards is not enough if you want your PDF document content to be accessible to all assistive technologies.Ĭase in point: consider STEM (Science, Technology, Engineering, and Mathematics) formulas.Īccording to PDF/UA accessibility guidelines, “All mathematical expressions shall be enclosed within a Formula tag and shall have an ALT attribute.” This post is the first in a series of how to make STEM content accessible in different document content. NOTE: Have been receiving lots of questions concerning the accessibility of math and scientific formulas in PDF documents.

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