The subroutine actually uses a string as a label. For example, a base string is made by turning the X/Y coordinates into a string and added to "RM". So let's say we have B$="RM0304", then we'd make R$="@"+B$ and we'll want to make a string for each bg layer as well so it would look like L1$="DAT:SC_"+B$+"_L1"