Hi again! I understand that „B.V.“ is entered in „detention detail/Haftart“ (I did so) whereas „Vorbeuge“ belongs to „reason for arrest/Grund“
Kind regards!
I agree with @u.sch in this discussion that the explanation in the Help-text is not quite clear as far as the difference between „Haftart“ (= prisoner’s category) and „Grund“ (= why a prisoner was said to be arrested) is concerned.