Oh, the way I mark blocks to be sewn is I number all the rows from A to whatever, and all the columns from 1 to whatever. Then I use Word to enter A1, A2,...B1, B2,... in a table and print in whatever font works best (as large as possible.) I cut the printout so that I have separate pieces of paper, usually about an inch square, for each block, and then I get down on the flower and carefully pin that paper to the upper left corner (always that corner!) of each block, stacking the blocks as I go. Then I start sewing them together, being careful to preserve the numbering and lettering sequence.