What is the meaning of (+0.300) marked in the beam concentration?

The centralized marking (+0.300) under the beam means that the elevation of the beam surface is 0.3m higher than the indoor floor (facing). Centralized dimension indicates the general value of beam, and in-situ dimension indicates the special value of beam. The centralized mark (+0.300) of the beam below refers to the roof frame beam, and (+0.300) indicates that the elevation of the beam surface is 0.3m higher than the indoor bottom surface (facing).