Nonetheless the only real solo certification says Advanced Diver and Solo and is not part of their related organization's technical courses though as has been pointed out certainly the skills are transferrable.
Not arguing, my opinion, a split up buddy group is not solo diving, it is simply a failed buddy system, accidental and an accident waiting to happen and is of no relation to intentional solo diving. I think the "buddy search" can probably be implicated in some lost buddy accidents as a precipitating cause of the final demise.
If I am diving with a buddy then I am buddy diving. If not I am solo and anybody in my vicintiy, sure I would help them if I can but I am not there to help them and may not be equipped to do so, I may not be paying them any mind, I may be focused on my lens. If you are buddy diving with me best make sure it is a mutual agreement, I would like to know
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