What are these words on the back of a קלף?
I recently saw a piece of קלף that had these words on the back:
Note: I'm talking about the words towards the bottom of the parchment, not Hashem's name.
Notice how the words are written facing the other direction from the regular words.
I have 2 questions:
- Does anyone know what these words say/mean?
- What is the source for writing them on pieces of קלף?