one of the elite military units. the Archontopouloi (Gr. ), were an elite military formation of the Komnenian era. In addition, there was also the Hetaireia (Gr. , "Companions"), which comprised the mercenary corps in Imperial service, subdivided in Greater, Middle and Lesser, each commanded by a respective Hetaireiarchēs. Organization There is much debate as to the exact size and composition of the imperial tagmata, owing to the inaccuracy and ambiguity of the few contemporary sources (military manuals, lists of offices and Arab accounts, primarily from the ninth century) that deal with them. Our primary sources, the accounts of Arab geographers ibn Khordadbeh and ibn Qudamah are somewhat ambiguous, but they give the overall tagmata strength at 24,000. This figure has been seen by many scholars, such as J. B. Bury and John Haldon, as too high, and revised estimates put the strength of each tagma at 1000–1500 men. Others, like Warren Treadgold and (in part) Friedhelm Winkelmann, accept these numbers, and correlate them with the lists of officers in the Klētorologion to reach an average size of 4000 for each tagma (including the Optimatoi and the Noumeroi, for which it is explicitly stated that they numbered 4000 each). The tagmatic units were all organized along similar lines. They were commanded by a domestikos, except for the Vigla, which was commanded by the Droungarios of the Vigla. He was assisted by one or two officers called topotērētēs "place-warden, lieutenant"(), each of whom commanded one half of the unit. Unlike the thematic units, there were no permanent intermediate command levels (tourmarchai, chiliarchoi or pentakosiarchai) until Leo VI introduced the droungarios ca. after 902. The largest subdivision of the tagmata was the bandon, commanded by a komēs "count", called skribōn in the Exkoubitores and tribounos "tribune" in the Noumeroi and Walls units. The banda in turn were divided in companies, headed by a kentarchos "centurion", or drakonarios for the Exkoubitores, and vikarios "vicar" for the Noumeroi and Walls units. The Domestic of the Schools, the head of the Scholai regiment, became gradually more and more important, eventually coming to be the most senior officer of the entire army by the end of the tenth century. The following table illustrates the structure of the Scholai in the ninth century, according to Treadgold: In addition, there were a chartoularios "secretary" () and a prōtomandatōr "head messenger (), as well as 40 bandophoroi "standard bearers"