Font Size in PX isn't accurate, why?

I do not know how Adobe specifies type size so perhaps the following has little relevance. On the off chance that it is similar to the foundry type that, as a youngster, I learned to set (and distribute it back into the job case after it had been used).

I searched around for a diagram that might be helpful when referring to type in terms of point size.

Note that the letter sits on a shoulder that is larger than the letter. This allows area for ascenders (lower case l, k and h, for example) and for desscenders (example: g, p and q)

In fact, the origin of the phrase "mind your p's and q's", meaning be careful, originated in letterpress shops where the metal letters are backward, easy for the novice to confuse.

In addition to the. face, ascender and descender there is additional blank space at the bottom of the shoulder so that, when several lines are set, the bottom of a descender will not butt the top of an ascender in the line below.

As a result, you cannot take a measure of the face and call that the type size. The point size is what is shown above as Point Body and includes the shoulder.

To repeat, when Adobe refers to point or pixel size, I don't know whether or not the presumed body is part of the point designation. I assume, in providing for line-below-line spacing, even without leading, they make the same accommodation.

Have you allowed for descenders and ascenders?

Dave