Please clarify the numbering system in Microsoft exams

I am trying to make sense of exam numbers in Microsoft Certification poster.

https://arch-center.azureedge.net/Credentials/Certification-Poster_en-us.pdf.

For example I notice most azure exam numbers start with 1xx. That gives me the impression that 1xx could be related to Infrastructure. But I am not sure if that is the correct understanding. For example all fundamental exams are numbered 9xx. So are exams numbered differently in role based certifications? What is the numbering pattern and practice in role based certifications?

Again one might assume that all architect exams may have the same number pattern but they don’t.

Some patterns emerge when it comes to Windows certification - 8xx.

Collaboration and communication - 7xx except MB 700.

So it appears even under role based certifications the numbering pattern may be different depending on the technology or platform or product. I have not found any authoritative material on the internet form anyone in Microsoft or an MVP on this topic. Some clarification on this topic will help to put at rest years of curiosity and confusion in the community. Thank you.