Roman numeral code: V / V / V
Scale notes: 6, #1, 3
Mode: major
Attributes: a further venturing away, further than 5 / 5.
This harmony takes 5 of 5 one step further, being the dominant harmony to 5 of 5.
It begins the powerful 3-step cadence 5/5/5 to 5/5 to 5 to 1.
The root of 5/5/5 is three dominant jumps away from the tonic. 5/5/5 is a major chord built on note 6 of the scale.
It is the same chord as 5 of 2, but has a different harmonic purpose.