In the middle Byzantine period (7th–12th centuries), the prefect was regarded as the supreme judge in the capital, after the emperor himself. His role in the economical life of the city was also of principal importance. The 10th-century "Book of the Prefect" stipulates the various rules for the various guilds that fell under the prefect's authority. The prefect was also responsible for the appointment of the teachers to the University of Constantinople, and for the distribution of the grain dole to the city. According to the late 9th-century "Klētorologion", his two principal aides were the "symponos" and the "logothetēs tou praitōriou". In addition, there were the heads (, "geitoniarchai", the old "curatores regionum") and judges ("kritai") of the city's districts (Latin "regiones", in Greek , "regeōnai"), the "parathalassitēs" (παραθαλασσίτης), an official responsible for the capital's seashore and ports, as well as their tolls, and several inspectors ("epoptai"), the heads of the guilds ("exarchoi") and the "boullōtai", whose function was to check and append the seal of the eparch on weights and scales as well as merchandise.