Vallum, the rampart of a Roman encampment, composed of earth with sharp stakes inserted in it, and derived from vallus a stake, is represented on coins of the Numonia gens struck by Numonius Vaala in 43 BC. The surname Vaala or Vala was given to him for successfully assualting the entrenchment of an enemy. It is thought that the form of a vallum may be seen on coins of Licinius I, Constantine the Great, Constantine II, etc, bearing the egend VIRT EXERC or VIRTVS EXERC, inany case this type seems to represent a camp on the top of which is standing the sun raising the right hand and holding a globe.