Discussions concerning the Uboat Commander's Handbook

[Paul Riley]

I thought it may be worthwhile starting a new post concerning the Uboat Commander's Handbook.This could involve discussions on tactics in general,and also with certain errors to be found in the document,which would no doubt cause some level of confusion for the reader.
I ordered the book 4 days ago and am awaiting its arrival from the US,but in the meantime I am reading an online version of the book,and have come across the first error (or at least I assume it is) in the document.It is concerning ASDIC and sound location in general.Below is the exact reference -

198.) During the night surface attack, the submarine can:
I. be sighted,
II. be sound-located,
III. be located by ASDIC.
I. Danger of Being Sighted.

I am concerned about lines II and III.On the surface a UBoat should be unaffected by ASDIC and or hydrophone detection in general,or this is the most common assumption by a lot of people.
I am thinking that it may have been a preliminary expectation of ASDIC in the very early stages of the war,when the Germans had little knowledge or experience of allied sound capabilities.
Or is it simply an error in the text?

Thanks.