if you tune your guitar dgdgbd[spanish tuning],youcan play tunes like wildwood flower and carter family songs plus five string banjo tunes using thumb for melody and brushing down with index and playing up with index,to get bum ditty rhythm of the banjo but using top string to replaceshort banjo g string,this is quite similiar to a 5 string banjo style known as thumb melody lead.not quite the same as harley but not disssimiliar.
this is also agreat tuning for playing melody picking with alternating basses[piedmont style guitar.
with this tuning if you replace the 5[a] string with an octave 12 string guitar string[3 gstring]youcan also play banjo tunes and do the bum dittyor clawhammer old timey etc as if you were using the high short g banjo string,so if you are used to playing 5string banjo you can do it on a guitar.