Is a multimeter with 1,200,000 counts actually a 6½ digit multimeter?

The 1.999999 is already a lie. A 6.5 digit meter should have \$10^{6.5}\$ = 3162377 "counts".

So, extending the lie, meters that have 3999 counts are described as 3-3/4 digit, when in fact they're barely 3.5 digit.

Lies, damn lies, and marketing. Maybe a class action suit is in order if you can claim you were hoodwinked by their fake "marketing digits".

To answer your title question, the meter in question is a 6.08 digit multimeter if it has 1,200,000 counts.

I think designing a more than 6 digit meter is a pretty impressive feat.

If you get off on precise numbers, then you're right, sure, go rain on their (publicity department's) parade.

It's interesting that a device intended for extreme precision should fall down in the precision of how it's described.

The additional overrange digit referred to as a 1/2 digit.

The overflow resulting resolution ratio with range and its name is insignificant anyways.

What really counts is accuracy.

That 1/2 digit typically shows only the values 0 or 1.

There may be some exceptions that are designed for +/-2.99 ... such as resistance overflow.

However anyone can take credit for it's definition, that's also insignificant. It is just common wisdom.

I once had a 10 1/2 digit digital counter too but resolution is insignificant usually compared to accuracy.