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**Abstract**

The branching fraction for D (exp(+) -> K exp(0) sub(L) Pi exp(+) is measured for the first time, using 281 pb exp(-1) of e exp(+)-e exp(-) collisions recorded by the CLEO-c detector at the Cornell Electron Storage Ring. The analysis employs a missing mass technique which does not require reconstruction of the K exp(0) sub(L) . The resulting branching fraction is (1.460 +- 0.040 +- 0.035 +- 0.005)%, where the first uncertainty is statistical, the second is systematic, and the last is due to the input value of B(D exp(+) -> K exp(0) sub(S) Pi exp(+)). Using an independent measurement of B(D exp(+) -> K exp(0) sub(S) Pi exp(+)), we calculate that the asymmetry between B(D exp(+) -> K exp(0) sub(S) Pi exp(+)) and B(D exp(+) -> K exp(0) sub(L) Pi exp(+)) is R(D exp(+)) = [B(K exp(0) sub(S) Pi exp(+)) - B(K exp(0) sub(L) Pi exp(+)]/[B(K exp(0) sub(S) Pi exp(+)) - B(K exp(0) sub(L) Pi exp(+))] = 0.022 +- 0.016 +- 0.018. This result rules out scenarios of maximal interference between amplitudes for D exp(+) -> K exp(0) Pi exp(+) and D exp(+) -> not K exp(0) Pi exp(+) , and it is consistent with theoretical predictions. Measurement of track and K exp(0) sub(S) reconstruction efficiencies is also discussed. This analysis provides systematic uncertainties used in the measurement of B(D exp(+) -> K exp(0) sub(L) Pi exp(+)) and in other CLEO-c analyses.