Need help in explaining this piece of tutorial code

1

i was mugging on this tutorial :

http://www.kirupa.com/web/xml/examples/sortedgradeslist.htm

and could not figure out this piece of code:

FIRST_SORT = function(a,b){ 
return a.attributes.first > b.attributes.first; 
} 
LAST_SORT = function(a,b){ 
return a.attributes.last > b.attributes.last; 
} 
GPA_SORT = function(a,b){ 
return parseFloat(a.attributes.gpa) < parseFloat(b.attributes.gpa); 
}

The return a.attributes.first > b.attributes.first will return what value?