I'm delving into the historical aspects of Bitcoin's development, particularly the encoding methods used in the early .dat files created by Satoshi Nakamoto. My focus is on understanding the specific patterns and encoding schemes employed in these foundational stages, specifically the use of uppercase hex letters for blockchain data representation and two distinct patterns: "FD FE FF" and "F%F%F%".

"FD FE FF" Encoding: I understand that these sequences are related to varint encoding, with each prefix indicating the byte length of the subsequent integer ("FD" for 2-byte, "FE" for 4-byte, and "FF" for 8-byte integers). This compact representation method is fascinating, and I'm eager to learn more about its application and technical details within the Bitcoin blockchain data structure.

"F%F%F%" Pattern: This pattern is less clear to me. It does not seem to align with standard hexadecimal notation or Bitcoin's varint encoding principles. Could someone shed light on the use and translation of "F%" in the early Bitcoin code or data formatting? Is this a custom encoding method, or does it have a specific application that is not widely documented?

I'm looking for documents, discussions, or any form of literature that might explain the rationale, usage, and technical specifics of these patterns, especially the elusive "F%F%F%". Insights into Satoshi's encoding choices or references to discussions in early forums or code comments would be incredibly helpful.

Thank you for your time and expertise. I'm looking forward to deepening my understanding of Bitcoin's technical history with your help.