How to measure LTE attachment time?

@mlw
that is not a good news…
Nevertheless, I found some structures which provides the following variables via the
* pCSDomain
* pPSDomain
* csAttachState
* psAttachState

But I did not find reliable information to make the distinction between them except that the last 2 ones seems to be used in callback function which is deprecated.
Do you know some places where it is possible to get documentation on it?
thanks in advance.
Johann