P_{i.j} or P_{j,i}

It's a matter of notation, but wikipedia says: If the probability of moving from i to j in one time step is Pr(j|i)=P_{i,j}, the stochastic matrix P is given by using P_{i,j} as the i^{th} row and j^{th} column element

http://en.wikipedia.org/wiki/Stochastic_matrix

I have seen either notation. Which is used in the course?