Split Posting table field in workflow

In v7.1, I have a table field setup and I've added it to a workflow task.  It shows up and I can enter data into it.  However, I can't figure out how to save that data anywhere.  On the Assign Data tab, I don't see any way to assign the data from the table field to the table field in the cabinet, or to a global workflow variable.  Because of this, I can't figure a way to then assign the next step to a department, since department is a column in the table field. 

Also, in web client, if I choose to store a document and enter data in the table field, if I accidentally add a new line to it, it requires that I enter data for that line (yes, I have some mandatory fields).  I cannot find a way to remove a line that was accidentally added.

Can you help me move forward with my workflow?

I think I have this figured out.  I can't write the table field data in the workflow back to the table field in the cabinet, but I can write columns of the table data to index items or workflow variables using an arithmetic expression.

I think I fixed the other issue also by not requiring any columns in the table field for the store dialog I was using.