This clause does not apply to castellated members.
The internal dimension of the opening, lw must satisfy either:
1: lw/d1 must be less than or equal to 0.10 for webs without longitudinal stiffeners.
or
2: lw/d1 must be less than or equal to 0.33 for longitudinally stiffened webs.
provided the longitudinal distance between boundaries of adjacent openings is at least 3 times the greatest internal dimension of the opening.
Only one unstiffened opening is permited at any given cross section unless analysis shows that stiffeners are not necessary.
The above is 95% of the text in the standard, the remainder refers to castellated members being designed by rational analysis.
Hope it helps.
regards
sc