如何确定零件的速度等级

我最近收购了一些极简主义的Spartan 6开发板。
电路板上的Spartan 6芯片标记如下图所示。
我需要一些帮助来确定零件的速度等级，因为标记不符合Xilinx在数据表中显示的格式。
有人知道吗？
迈克尔卡拉斯



以下为原文

I recently acquired a couple of minimalist Spartan 6 development boards. The Spartan 6 chip on the board is marked as shown in the picture below. I need some help figuring out the speed grade for the part as the marking does not follow the format that Xilinx has shown in the data sheet. Does anybody know?

Michael Karas