The "UPD" version is not the end. Developers are currently working on version 2.0, which promises:
Fixing the aspect ratio for modern displays. What is the PS2 ELF Extractor UPD? Ps2 Elf Extractor UPD
I notice you’re asking about a “PS2 ELF Extractor UPD” and mention a “solid paper.” It sounds like you might be looking for an updated tool or technical documentation related to extracting or analyzing ELF executables from PlayStation 2 software. The "UPD" version is not the end