[jhowell]

Originally Posted by Bluebotlabs

The actual NMDL data itself: ... Seems to be base64 encoded binary... unfortunately since it's encoded binary even after decoding it's not exactly easy to understand...

You are correct, that is base64. That is how binary blobs are presented in Ion text format. In the actual notebook file that data is binary.

I was able to work out what that data represents by trial and error testing. It is a compressed list of integer values. The ad hoc compression scheme used takes advantage of the fact that sequential points on a stroke are very close in value to each other.

The decoder for that data will be part of the upcoming KFX Input calibre plugin release which will be able to decode Scribe notebooks.

Originally Posted by Bluebotlabs

Additionally, something I found interesting, KDF files did exist before the scribe... but there's very little information on them

https://www.kdpcommunity.com/s/quest...language=en_US

Yes, KDF files are the main component of KPF (Kindle Package Format) produced by Amazon's Kindle Create software. The main difference between KDF and KFX is that KFX is a compact binary format and must be completely rewritten if it needs to be modified. KDF on the other hand is stored in an SQLite database and can be updated on-the-fly.

Originally Posted by Bluebotlabs

Perhaps it is ION?
https://amazon-ion.github.io/ion-docs/

Ion is the coding that underlies both KFX and KDF formats. It has a compact binary representation that is used in those formats. It also has an equivalent textual representation (somewhat like JSON) that can be used when Ion content needs to be understood. The code shown in the spoiler in this post is KDF data presented in Ion text format.