cannot understand the function of code 'data_np=data_np/200.0'

[lsq117]

in dataset_lits_train.py, def get_np_data_3d(),line44:
def get_np_data_3d(self, filename, resize_scale=1):
data_np = sitk.GetArrayFromImage(sitk.ReadImage(self.dataset_path + '/data/' + filename, sitk.sitkInt16))
if self.resize_scale !=1.0:
data_np = ndimage.zoom(data_np, zoom=self.resize_scale, order=3)
data_np = data_np.astype(np.float32) # --------不理解的地方二
data_np=data_np/200.0 #--------------不理解的地方一

i cannot understand the function of this code:'data_np=data_np/200.0'，why 200 divided by 3, how do we get the parameter 200? assign at random?or other reason?
Could anyone answer my question?