Until the CTPE ceased, I gave a PMB to all players and substitutes that lasted a minute. It covered advantage, the set, the LO and appealing. It was simple, clear and set my stall out - and, on occasion, some players would join in with the final words! As long as I refereed to these simple instuctions, there seemed few problems.
However, I was advised by an assessor that I was opening myself up to a potential lawsuit if a major incident should occur - I should brief only the front row and strictly according to the guide lines - but he could provide none.
Since then, I do no PMB and until such time as I am given an official brief that is applicable to all, I will not do so.
At the first scrum, I hold up the engagement and inform both packs that all scrums are uncontested until the ball enters the tunnel and that all binding in rugby football must be shoulder to wrist. I then call crouch and get on with the game. I find that this is simple, clear and obvious and lets all forwards know exactly my requirements and is the nearest and only thing that gets near to a BMB.
Normally, apart from an annual MOT, I do not get assessed except this year, when I have been assessed three times - all of which were exemplary but none of which mentioned my not giving a PMB.
NM