[en] There have been a proposal (accepted - E777) and a letter-of-intent to search for K⁺ → π⁺μ⁺e^- to a branching ratio better than 10^-11. This motivation is to test different types of lepton number conservation - specifically, there is a boson in technicolor models which would allow such decays at a level around 10^-10. This note discusses the E777 experiment, reasons for doing the experiment at the AGS, and the prospects for looking for even smaller branching ratios. A level of B.R. < 4.8 x 10^-9 (90% C.L.) for K⁺ → π⁺μ⁺e^- was achieved in a CERN experiment designed to study Ke4 decay. That experiment used a separated 8 x 10⁴/pulse K⁺ beam with a PWC/spark chamber detector and no muon identification. E777 will use an unseparated beam with 2 x 10⁷K⁺/pulse, PWCs, and muon identification. Cherenkovs will be designed to not misidentify particles, at a reduced efficiency. For example, two counters will be filled with H₂ gas at atmospheric pressure to identify electrons. This reduces delta-ray contamination, at a cost of reduced efficiency for identifying the electrons. They chose a K⁺ momentum of 6 Gev/c (and, thus, to do the experiment at the AGS) for good particle identification