In most cases, formulas for native speakers have been applied to L2 texts.
the validity of such an approach is far from established, because it relies on three suspect assumptions : (1) the understanding of readers in the L2 is comparable to that of native speakers, (2) the textual features considered in L1 formulas are relevant to L2 reading, and (3) the weighting of these variables may be the same in a formula for L1 and L2.