Understanding Syntax of .lib spice file (Memristor)

I was creating a memristor library on Pspice. I sucesfully did it but I was trying to understand the syntax. I found this off a iEEE published paper and wanted to know of what the syntax means.

It is shown below. I understand Line 1 is creating a memristor with input signal - 1, output signal - 2, and state signal - 6. However, what does Eres, Vsense, Fcopy, etc mean? Is Vsense the voltage defiened for Vdd and Vss? And what about the LRS/HRS resistance values for memristors? What does "Vsense 9 4 DC 0V" mean? I just need a quick understanding of the syntax/variables. Unless you guys have any link/website where it shows this. 

1. .SUBCKT memristor 1 2 6
2. Eres        1    9    POLY(2) (8,0) (10,0) 0 0 0 0 1
3. Vsense    9    4    DC 0V
4. Fcopy        0    8    Vsense 1
5. Rstep        8    0    1K
6. Rser        2    4    10
7. Gmem 6 0 VALUE={I(Vsense)*max(v(6,0)*(1-v(6,0)), 0)}
8. Cmem     6 0 50nF
9. Ecpy    10 0 VALUE={min(max(v(6,0), 0), 1)}
10. Rsp        6    0    1000Meg
11. .ENDS
12. *$