Consider the Feynman diagram below from, http://hyperphysics.phy-astr.gsu.edu/hbase/particles/expar.html where I assume time runs upwards and the gluon in the graphic runs horizontal and is labled as a green_antiblue gluon. If the gluon runs horizontal can one still label a gluon as being green_antiblue? Only if the gluon is not horizontal can we specifically label it? Hope my question is not too confusing. Thanks for any help!