What does the number 6, 10, 900, 1000 mean in the QGM block machine?

Take block machine QT6 as an example, 6 means the brick machine could make 6 pieces of hollow blocks at the size of 390*190*190mm. The same goes with QT10. For the ZN900C, ZN1000C, these two concrete block machines are updated with Germany Zenith design after 2014. ZN900C and ZN1000C respectively makes 9 and 10 pieces of the same cement blocks mentioned above.