Okay, the user wants me to translate "sub-grade" into Finnish. Let me check what "sub-grade" means. It could refer to a lower grade or a subsidiary grade. In Finnish, "grade" is "arvosana" or "luokka" depending on context. "Sub-" might translate to "al-" or "sivu-". So "sub-grade" could be "alaluokka" or "sivuluokka". But I need to make sure. Let me think of examples. If it's about academic grades, maybe "al-arvosana" but that's less common. Alternatively, "sub-grade" might be a technical term. Maybe "alaluokka" is the most accurate. I'll go with that.