What's the "battery indicator mark"?

[Auf los!]

I want to top off my battery (a Porsche-labeled Moll Kamina) with distilled water, and the owner's manual says to fill to the battery indicator mark, but I unscrewed a cap and looked down inside the cell, and I am confused as to what and where the mark is.

Descending from the cap threads into the cell is a metal "bracket" with a bend at the end. Is that bend the indicator? I should fill up each cell until it reaches that bend at the end of this sorta bracket?

TIA!