What is the (exact) naming scheme for ASUS monitors?

ASUS monitors have names such as "MG28UQ" or "PA27AC".

I don't even know exactly what the name consists of. Obviously, the diagonal length is in there - a two-digit number in inches.

Can someone explain the meaning of the prefix and suffix parts of the naming scheme (before and after the diagonal length)?

_{PS This question is similar to: What's the (exact) naming scheme for Dell monitors? ... but for ASUS rather than Dell.}

Here's what I've figured out so far:

The name seems to be made up of four sections:

1. Quality category:

   Professional | Mainstream | Value

2. Use focus:

   Business | Art | Gaming | Narrow bezel | X - stylish design

3. Diagonal length (inches, probably including bezel)

4. Potential extra digit (perhaps actually part of previous or next section?)
5. Extra codes

But I'm still looking for information about the third category - qualifiers and "feature flags". As I gather it, I'll add it here:

• Q: DisplayPort input
• H: (HDMI input?)

Also, the extra digit does not indicate the year the model was introduced, since some models don't have it, and some models have a digit that is at least 2 past their year of release (e.g. MG278Q introduced in 2015 or 2016).