For 1 param in rel I use:
<a rel="all">All</a>
var group = $(this).attr('rel');
How to extract multiple rel attribute from link?
<a rel="all test1 test2">All</a>
TNQ!
var groups = group.split( ' ' );
See this test.
Or, if you want to account for possible repeated whitespace chars in between them
var groups = group.split( /\s+/ );