See also post and 200
The standard tuning of the guitar comes from a scale LIKE :
F2-Bb2-D3-G3-B3-E4-G#4-C#5-F5
So we may repeat the pattern 4-3M-4 D3-G3-B3-E4 of the standard tuning of the guitar to the
4-3M-4-3M-4 or F2-Bb2-D3-G3-B3-E4
We play this tuning as two 4-strings Greek bouzouki
The high D3-G3-B3-E4 (4-3M-4) in G major
The low F2-Bb2-D3-G3 (4-3M-4) in Bb major