1. The problem statement, all variables and given/known data Not a specific problem; I'm trying to understand what the notation means; I'm using primarily Griffiths, Marion and Jackson textbooks. The notation for a matrix, with the superscript row index and subscript column index I understand. For the EM field tensor, Griffiths has both indices superscripted, and Marion has both subscripted. My questions are: 1. What is the difference? 2. What is the meaning when they are both on the same level? I assume one is rows and one is columns - but which is which? 3. When you take a derivative of the tensor, what exactly are you doing in terms of the indices of the tensor and the index of the variable of integration? 2. Relevant equations 3. The attempt at a solution I've searched Boas, Arfken & Webber, Wikipedia, and some other web sites to no avail.