Here’s a short, good story based on that phrase:
for installing content directly to the console's internal memory or an external USB drive. Unlike standard disc images (ISO or WUD), WUP files are "installable" packages that allow games to appear on the Wii U home menu just like official digital purchases. How WUP ROMs Work on Wii U wii u wup roms work
Launch WUP Installer GX2 from the Wii U menu or Homebrew Launcher. Here’s a short, good story based on that
When software is installed to the NAND (internal memory) or a USB drive formatted by the Wii U, it is stored in the WUP format. Encryption: All official software (WUP) is encrypted
.app files into RAM just before execution.Verdict: For real hardware, WUP is the gold standard. For emulation, decrypted WUP or WUD is better.
The keyword "work" depends on your platform: