Dashed line(s) in Text Editor

What does the dashed line in the new text panel relate to? I’ve been searching the tutorials, etc. and can’t find what they indicate.
Sometimes the cursor is above and the line remains, sometimes it’s below, sometimes the line disappears.
For example, in the Interactive Tutorial document it is sometimes present (sometimes two), sometimes not and the cursor sometimes above, sometimes below.
Occurs in blank New Text panel. Indispensable program, just would like to know how to use this line.

Best guess, you are seeing the text of multiple binder items (folders and/or documents) presented together, with the horizontal dashed line separator between them. This can be toggled on and off via the “scrivenings” mode button top middle of the toolbar (set of three buttons: scrivenings, corkboard, outline), which presents the explantation “view the documents as scrivenings…” if you hover the mouse pointer over it for a bit.

In the interactive tutorial, see Part 2: Organization > Step 11: Scrivenings.

I took a stab at discussing/explaining this in the following forum post. Read both of my rather lengthy posts in that thread.
… and possibly also here…

Hope that is of some assistance.