A Christogram was a Christian symbol that began to appear on Roman coins after the emperor Constantine issued the Edict of Milan in A. D. 313, permitting all Romans to worship as they pleased. With the Christian persecutions ended, Christian symbols gradually started to appear on coins. The Christogram was the Greek letter X (Chi) superimposed on the letter P (Rho) and was the monogram for Jesus Christs name. Another variant was a cross instead of an X superimposed on a P. The Christogram was often displayed on a labarum, a Christian battle standard in the form of a pennant used by late Roman armies.