The bottom four strings of a guitar in standard are EADG (bass to treble)and the mandolin is symetrical to this GDAE. The bottom four strings of a guitar in DADGAD are DADG and Many of us tune our Bouzoukis, Octave mandolins... GDAD, and get the same modal type of sound.

A question about octave mandolins and octave mandolas. An octave mandolin is an octave below a regular mandolin, therefore it is GDAE (B.to T.) Am I to assume that an octave mandola is an octave below a regular mandola, therefore tuned CGDA?

I know that these instruments seem to be called whatever the maker or player wants to call them. I think of a bouzouki as a Greek instrument, and at one time I hated the term being applied to a flat backed instrument, but I've learned to accept it. The same is true for the term Cittern. There is already an instrument called a cittern, so it seems that we should think up a new term for the modern "cittern". I know my protests are all in vain and I should get used to people calling these by any name they like. I call mine a Monster Mandolin.