Fermilab high-energy photoproduction experiment E687 provides a high s
tatistics sample of the decay mode D+ --> K0BARmu+nu (charge conjugat
es are implied). Our analysis yields a branching ratio of GAMMA(D+ -->
K0BARmu+nu)/GAMMA(D+ --> K-pi+pi+) = 0.56 +/- 0.04 +/- 0.06. The rat
ios of the form factors governing the decay are measured to be R(upsil
on) = 1.74+/-0.27+/-0.28 and R2 = 0.78+/-0.18+/-0.10, implying a polar
ization of GAMMA(l)/GAMMA(t) = 1.20+/-0.13+/-0.13 for the electron dec
ay. Finally, we report new limits on the decay modes D+ --> K-pi+mu+nu
(nonresonant) and D+ --> K0BARpi0mu+nu.