Order Statistics
For a sample $\mathbf{x} = ( x_1, x_2, \ldots, x_n )$, the $i^\textrm{th}$ order statistic $x_{(i)}$ is the $i^\textrm{th}$ element in the sorted version of $\mathbf{x}$.
Example
$$ \mathbf{x} = (2, 3, 4, 1) $$$$ x_{(1)} = 1, \quad x_{(2)} = 2, \quad x_{(3)} = 3, \quad x_{(4)} = 4 $$
$$ \mathbf{x} = (2, 3, 4, 1) $$$$ x_{(1)} = 1, \quad x_{(2)} = 2, \quad x_{(3)} = 3, \quad x_{(4)} = 4 $$