Erlang code explained -

I'm having trouble with my head around the following erlang code

  - module (Threesix). Export ([quicksort / 1]). QuickSport (Pivot, left, right, [] = _ Src) - & gt; {Left, pivot, right}; QortSort (Pivot, left, right, [HK] = _ Src) when H & lt; Smoke - & gt; Quortsort (pivot, [h | left], right, t); QuickSport (Pivot, left, right, [HK] = _ SRC) - & gt; QuartersSoft (Pivot, Left, [H | Wright], T) Quickskort ([]) - & gt; []; Quick List ([H. T] = _ List) - & gt; {Left, pivot, right} = quicksource (h, [], [], t), exactest (left) ++ [pivot] ++ quicktest (right).  

I am talking specifically about the use of _Src and _List in the parameters.

Is this only for the document because I do not know why they use it?

Yes, they are only for documentation, they are not actually being used (as the major underscores Is represented by).