Shirts must be tucked into pants so that the belt or waistline is clearly visible all the way around the waist.
(Shirts; must be tucked; into pants; so that the belt or waistline is clearly visible all the way around the waist) (the belt or waistline; is; clearly visible all the way around the waist)
Shirts the belt or waistline
must be tucked is
into pants so that the belt or waistline is clearly visible all the way around the waist
clearly visible all the way around the waist