The parameter multiple takes the value M if the object belongs to a multiple system. For example, a galaxy belonging to a pair of galaxies have multiple=M . Presently multiple accounts for the association in projection on the sky and therefore does not reflect for sure a physical association: members of "false" pairs will have multiple=M . ... The simple membership to a cluster of galaxies does not imply a galaxy to carry multiple=M . ... HyperLeda . ...