tsmc电阻建模使用的bsource模型是什么？

请问tsmc电阻建模使用的bsource模型是什么（如下）?在模型文件中好像找不到对bsource的定义。谢谢
R1 (n1 n2) bsource r=rsh * (l / (w - dw)) * (1 + vc1 * abs(v(n1,n2)) + vc2 * v(n1,n2)
+ * v(n1,n2)) * tfac

bsource is defined by spectre, not in the model file.
Type spectre -h bsource in the terminal for details.