. "Any process that activates or increases the frequency, rate or extent of the covalent addition of methyl groups to histones." . . . "positive regulation of histone methylation" . "activation of histone methylation" . "stimulation of histone methylation" . "up regulation of histone methylation" . "up-regulation of histone methylation" . "upregulation of histone methylation" . . . . . . . . .