description: The abbr tag allows you to specify abbreviations with titles, which will be displayed when you hover over the indicated text. The abbr and acronym tags are usually displayed the same in browsers, and you can use either depending on whether you want to display abbreviations, acronyms or just have extra information. This is an inline tag and no block level tags can be placed inside, however other inline tags can be used if nested correctly. If the abbreviation's title contains complex characters, place it in quotes. SMF

example: [abbr="a.k.a. [Unknown]"]Unknown W. Brackets[/abbr]

result: Unknown W. Brackets;