I recently came across a 15 string fretless Zither that says "Citara Diadactica" across the front of the box. I found that Citara means Zither, but I have no idea what Diadactica means. If anyone knows, could they please tell me:
a) What some common tunings are for the instrument
b) What type of strings to use. Some of the strings are broken on the instrument, but I have no idea whether I could use guitar strings, and if so, what gauge I could use.

Thanks for any help.