For example, she can hit notes below the not fingered «open» G string — normally the lowest note in standard tuning — into the cello range without altering the instrument's tuning. (scientificamerican.com)
Chromatic: Standard tuning deal with 6 tones; Chromatic, 12. (geekwrapped.com)
This is our basic model that trains teachers, staff, and volunteers to play simplified guitar, sing and lead songs first in Open G tuning, then in standard tuning. (guitarsintheclassroom.org)