Leo VI ruled from 886 to 912 and had Constantine VII crowned co-emperor as an infant in 908, largely to secure dynastic succession after the deaths of his previous heirs and the canonical controversy surrounding Constantine's own legitimacy — he was the son of Leo's fourth marriage, which the Orthodox Church refused to recognize. The patriarch Nicholas Mystikos excommunicated Leo over it. This joint issue was struck during the four-year window when both names held simultaneous imperial standing, giving it a narrow chronological bracket that tightens attribution considerably.
Leo VI ruled from 886 to 912 and had Constantine VII crowned co-emperor as an infant in 908, largely to secure dynastic succession after the deaths of his previous heirs and the canonical controversy surrounding Constantine's own legitimacy — he was the son of Leo's fourth marriage, which the Orthodox Church refused to recognize. The patriarch Nicholas Mystikos excommunicated Leo over it. This joint issue was struck during the four-year window when both names held simultaneous imperial standing, giving it a narrow chronological bracket that tightens attribution considerably.