May a Catholic be an attendant at a non-Catholic wedding? May a non-Catholic be an attendant at a Catholic wedding?

According to the 1993 Directory for the Application of Principles and Norms on Ecumenism: "Members of other Churches or ecclesial Communities may be witnesses at the celebration of marriage in a Catholic Church. Catholics may also be witnesses at marriages which are celebrated in other Churches or ecclesial Communities." (n. 136)

This permission only applies to other Christian churches. Weddings between non-Christians are marriages but not sacramental marriages.