How does the Log my Certifications work?

Anyone know the intent behind the "Log Your Certifications" when editing a dive?

Is it meant to be logging the certification used for the dive?

Is it meant to be marking the dive that is used for certification?

Also, when looking at "Diver Certifications", there is a count of "Dives Since Certification", but this number seems to be somewhat inaccurate. 

When clicking on "Dives" (which I associate with the number of dives since certification), it only shows the dives where I've actively 'logged your certification' (a number not matching the dives since certification).

If I log a certification on a dive, it then increments the Dives Since Certification number - so that if I mark all my dives, I get a number that far exceeds my actual dive count.

As an example, for my Open Water certification, I would expect the dives since certification to equal my dive count minus the four dives done for certification. But it's far lower. If I log the Open Water certification on all my dives, I get a number that far exceeds my total dive count. 

What's going on?