Need help interpreting this drawing feature control frame A, Is it right to refer the datum B in feature control frame to which it is attached?

[shiva@im_engineer]

 

[jassco]

Datum feature "B" is self-referenced.

 

[3DDave]

The feature control frame for datum feature B should only have a perpendicularity geometric characteristic symbol and only reference datum feature A.

Is this from a text book or a test?

 

[shiva@im_engineer]

The feature control frame for datum feature B should only have a perpendicularity geometric characteristic symbol and only reference datum feature A.

Is this from a text book or a test?

Text book

 

[3DDave]

What was the discussion about this figure in the text book?

 

[shiva@im_engineer]

It was an execise, to find out permisible datum shift at each reference frame
Then i observed this if a datum is referenced at the same place where it is defined how can i calculate datum shift and it didnt make sense to me

 

[shiva@im_engineer]

Of course Solution in the book is zero, but found no explanation

 

[greenimi]

Of course Solution in the book is zero, but found no explanation

Would you mind to provide the name/edition of the book and the author?

 

[shiva@im_engineer]

Fundamentals of GD&T by Alex Krulikowsky

 

[greenimi]

Fundamentals of GD&T by Alex Krulikowsky

Which page?
Also which edition?