GRIB data format investigating octets of sections with Python

I’m trying to learn GRIB data format and I found this helpful guide to dive into

https://www.wmo.int/pages/prog/www/WDM/Guides/Guide-binary-2.html#Section3.

I had an experience with Gdal and Pygrib. Yet, I wanted to dive into for deeper knowledge on this data format.

How can I learn GRIB data format more deeply? There is not enough resources to learn it and I’ intermediate with the programming