metatorium

There is a partial clothing with the insignia in the metatorium before the ceremony begins, but the ritual centres in the conferring of the chlamys and crown.

The Catholic Encyclopedia, Volume 4: Clandestinity-Diocesan Chancery 1840-1916 1913

Finally, the emperor leaves the church wearing his crown and going to the metatorium seats himself upon his throne while the dignitaries (axiomata) come and do homage by kissing his knees.

The Catholic Encyclopedia, Volume 4: Clandestinity-Diocesan Chancery 1840-1916 1913