DELETE TO BEGINNING OF LINE - (CTRL/U)

Used to delete all the characters in the current line to the left of the
cursor.  If the cursor is located at the left margin, no action is taken.
The deleted text in placed in the deleted line buffer.

UNDELETE LINE - (GOLD CTRL/U)

Used to insert the contents of the deleted line buffer into the line at the
current position.  This may cause the line to be automatically wrapped.