ns are defined at two locations, and so it is possible to mount two kinds of internal equipments at the same level. [0008] However, such vertical frames are poor in workability because, as shown in FIG. 58, all sides 45, 46 directed toward outer walls abut against outer walls 47 of a front door 42 and a side panel 41 and equipment mounting holes 44 are formed on sides 48, 49 directed inward from t