It's likely a sprintf. They're not Luma "variables", they're in the mset code.Regarding the custom version string feature: Are there any other variables I can specify besides %d and/or %ls? If so what are they and what do they display? I tried looking at the source for that commit to ascertain but couldn't. Though I did figure out the requirement that it be less than or equal to 19 chars. I myself am not a developer but sometimes things are obvious enough by reading the source. This one isn't though. Does some 3DS library create those variables or something?