@neauoire Sorry, I didn't provide enough context. Suppose you have an tal program and you call a function that is not defined in the source code, but you have a .rom and .rom.sym for it. From the .rom.sym you can get the address for the label, but that will in general not work because you need to combine the roms for both. So you'd need to apply some offset to the rom so that its content fits after the content of your source file. For that you'd need to know at which address your source ends.