Medieval Greek (also known as Middle Greek or Byzantine Greek) is the stage of the Greek language. It was spoken from 330 to 1453, mostly in the Byzantine Empire.
↑The separate code "gkm" was proposed for inclusion in ISO 639-3 in 2006. The request is still pending. ("Change Request Documentation: 2006-084". sil.org. Retrieved 2018-05-19.)
Further reading
Andriotis, Νicholas P. (1995). History of the Greek Language. Thessalonica, Greece: Institute of Neo-Hellenic Studies.