Tool Where to find the C4 file with experience points table?

Question is in the title. I'm using the 656 C4 client and developing my own server in C++. When I send the StatusUpdate packet with experience, the %xp bar changes, so the client knows about the amount of experience for each level. Where can I find this and extract it? I am not interested in using another server/datapack experience table, only looking to learn where/how to extract this myself.

Thank you.

Edited April 28Apr 28 by Chnossos
Precisions around own server