Curly brackets – also called braces or squiggly brackets in the US – are used in specialized ways in poetry and music (to mark repeats or joined lines). The musical terms for this mark joining staves are accolade and "brace", and connect two or more lines of music that are played simultaneously.[12] In mathematics they delimit sets, and in writing, they may be used similarly, "Select your animal {goat, sheep, cow, horse} and follow me".

http://en.wikipedia.org/wiki/Bracket