We perform a general reduction of the open membrane metric in a worldvolume direction of the M5-brane. Using reduction rules analogous to the bulk, we show that the open membrane metric leads to the standard open string metric and open string coupling constant on the D4-brane only for an "electric" reduction in which case the open membrane metric has no or-diagonal components and the Born-Infeld curvature tensor is a matrix of rank 2. Instead, if we perform a general reduction, with nonzero or-diagonal components of the open membrane metric, we obtain a rank 4 Born-Infeld tensor corresponding to a bound state of an open string with an open D2-brane. Next, we identify and reduce a 3-form open membrane "theta tensor" on the M5-brane which red...