I'm reading a book and one section is talking about the mesh regarding the Riemann integral. The section I am having trouble with is this: " Now let the mesh of the partition go to zero, i.e: $max(t_i - t_{i-1}) \rightarrow 0$ If we proceed in this way, the points $t_i = t^{(n)}_i$ clearly have to depend on $n$ but we suppress this dependence in our notation. "
My question is; what is $t_i^{(n)}$? Specifically the ^(n). This isn't raising $t_i$ to the power of $n$ so what is the $n$ representing?