Terminal charge in the electrostatic simulation

I am working on a 2-D electrostatic simulation now. I was confused on the derived valuse of terminal charge.

As we can get the line integration terminal charge (es.nD) with the unit C/m or the line average terminal charge (es.Q0_1) with the unit of C, my problem is, what is the difference bewteen them? I can't find the exact explaination on these values in the help documentation. Can someone tell me about this problem?

Thanks in advance!