Status, methods and aims of the knee investigations at CR spectrum

Usually it is supposed that the definition of the CR mass composition in knee region is the key to problem of CR spectrum modification in this range. However tens of experiments done for the last half a century, have not decided this problem. The possible causes of fiasco and arguments in favour of necessity to reformulate a method of attack are discussed. It is formulated that the first experimental task now is to solve a more simple problem: is there abnormal CR component in knee field or not. It seams that impossible to formulate correctly more common problem of mass composition without solving of this one. The observational basis is discussed. The hypothesis of strange quark matter is suggested for the abnormal component.