Okay, the user wants me to translate "sub-program" into Simplified Chinese. Let me think about the correct term here. In Chinese, "sub-program" is commonly translated as "子程序". I should check if there's any alternative term, but I think "子程序" is the standard one. Since the user specified to output only the translation without explanations, I just need to provide "子程序" directly. No need for extra text. Let me make sure there's no other possible translation. Yep, "子程序" is correct. Alright, that's the answer.