The score_threshold_ of 4-points congruent sets algorithm in PCL

  3d-reconstruction, c++, point-cloud-library, windows

In the "ia_fpcs.h" which is the head file of the 4-points congruent algorithm in PCL, there is a parameter called "score_threshold_" , as shown in the figure below.The code is in lines 492 through 495.
enter image description here

As described in the source code, if the user does not give this parameter, it is set to "approximated overlap". However, in the implementation file("ia_fpcs.hpp"), this parameter is assigned to "1- approximated overlap", as shown in the image below.
The code is in lines 308 through 310.
enter image description here

Did I misunderstand? I am so confused about this. The version of the PCL is 1.10.

Any suggestions will be appreciated.

Source: Windows Questions