abbr Abbreviation (NISO JATS table model)
An abbreviated version of the cell’s content. This allows visual browsers to use the short form if space is limited, and non-visual browsers can give a cell’s header information in an abbreviated form before rendering each cell. (This attribute is based on and intended to be converted easily to the XHTML abbr attribute.)
As an example: this abbreviated version of the cell’s content may be rendered by user agents when appropriate in place of the cell’s content. Abbreviated names should be short since user agents may render them repeatedly. For instance, speech synthesizers may render the abbreviated headers relating to a particular cell before rendering that cell’s content.
Caution: This attribute has not been widely supported.