Access this via File > Setup > Source profiles:
Source profiles is a powerful feature when exporting your song as source. Indeed, you may want to target a specific CPU, and more importantly, a specific assembler. You want your assembler to be able to understand the exported source. A few factory profiles are already present, but you may want to create specific ones.
Factory profiles are all marked “read only”, as the greyed-out items show. Press the Plus icon at the top-right to duplicate the currently selected one. The new profile is ready for modification. You can rename and delete it via the icons at the top-right.
Each item must have a “{x}” which will be substituted with the value to encode. This enables the most complex syntax and as multi-line is possible, you can even encode macros if you wanted to.
An export button at the bottom-left exists to use the profile into the command line tools.