A Line in Fourths ii-V7 - 027 Trichords
As a technique for melodic and harmonic improvisation, 027s began to show up regularly in the early to mid 1960's in solos and compositions of such pioneers as McCoy Tyner, John Coltrane, Joe Henderson; Woody, Wayne, Herbie .....y'know; them guys.
The use of the 027 trichord, as a basic melodic unit, was and is a practical way to break free of the standard bebop scalar motif approach. It not only opens the door to a more intervallic melodic line (perfect 4ths, pentatonics), but can easily lead to the creation of an inside-outside (and vice versa) tension and release approach to building improvised and composed melodic lines; not to mention the potential for piquing ones interest in other types of trichord units (013, 025, etc).