Bruck blanking sequence

Does anyone remember details of the Bruck blanking sequence in a 625 PAL signal. I have tried to find a description of it on the internet with Googal without success. In particular I was looking for a diagram showing the field blanking with the Bruck blanking sequence highlighted over 4 fields.

2" quadruplex VTRs made by RCA, in particular the TR70B, used the Bruck blanking to set the timing of the edit pulse on the control track.

If the Bruck blanking sequence was wrong then the timing of the edit pulse could be 2 fields delayed compared to a standard recording and the recording would playback out of sync with the studio or presentation SPG.