Is there any difference in superscript and subscript notation in finite difference method

Is there any difference in superscript and subscript notation in the finite difference method? I see the same paper use (superscript for $$x$$ and superscript for $$y$$ notation) and (subscript for x and y notation)

• Please do not post images of math. Use MathJax. – G. Smith May 24 at 17:54
• I see the same paper use (super subscript for $x$ and superscript for $y$ notation) and (subscript for $x$ and $y$ notation). That’s not true. Those equations consistently use subscripts for spatial indices and superscripts for temporal indices. And did you mean to write “super subscript”? – G. Smith May 24 at 19:32

• If the OP's examples, index $l$ represents the time step and $i$ and $j$ represent the 2-dimensional mesh of points in the model. Using a notation like $T_{i,j}$ and $T_{i,l}$ would be confusing since the two pairs of subscripts mean different things. – alephzero May 24 at 18:45
• @Abinash $T_{i,l}$ would be non sense since i indicates one of the spatial dimentions and l indicates time, and not a different spatial dimension. But again, the distinction was meant for the author to make things clearer, it doesn't mean that it would be wrong to write l down, just more confusing. – Rafael Rodríguez Velasco May 24 at 18:57