What is "kletorologion"

The Klētorologion of Philotheos , is the longest and most important of the Byzantine lists of offices and court precedence ( Taktika). It was published in September 899 during the reign of Emperor Leo VI the Wise (r. 886–912) by the otherwise unknown prōtospatharios and atriklinēs Philotheos. As atriklinēs, Philotheos would have been responsible for receiving the guests for the imperial banquets (klētoria) and for conducting them to their proper seating places according to their place in the imperial hierarchy. In the preface to his work, he explicitly states that he compiled this treatise as a "precise exposé of the order of imperial banquets, of the name and value of each title, complied on the basis of ancient klētorologia", and recommends its adoption at the imperial table.