Why do I get bad offsets when plotting MACRO modules by byte? When plotting MACRO modules by byte, the offset is actually from the beginning of the module, including the data psects. You get bad offsets because the linker moves the psects around based on the psect attributes. Thus, the offsets you get may have no relationship to any listing you have. However, if you use PLOT ROUTINE foo BY BYTE, then the offsets will be from the beginning of the routine. (This will only work if you have an .ENTRY foo ... directive in your program.)