3 consecutive gracenotes, usually interjected between a non-stressed and a stressed crotchet of equal pitch; Open style pipers play the E-roll by lifting the chanter off the knee at raising their 3rd lowest finger:

(e¹) - a¹-e¹-d♯¹ - e¹; *(e¹) - a¹-e¹-d¹ - e¹; (f♯¹) -a¹-f♯¹-e¹ - f♯¹; (g¹) - a¹-g¹-f♯¹ - g¹; (a¹) - b¹-a¹-g¹ - a¹; (b¹) - c²-b¹-a¹ - b¹; (c²) - d²-c♯²-b¹ - c²; (e²) - a²-e²-d♯² - (e²); &c.
NB: Example(s) to be replaced with staff-notation.