The GR-33 had 128 User patches and 256 Preset patches (which you couldn’t overwrite). For a touring guitarist or a session player, that was never enough. The Librarian function allowed you to build massive banks on your computer.
: Uses MIDI System Exclusive (SysEx) data to back up and restore the device's entire memory, including program banks and system settings. Automation Roland Gr-33 Editor Librarian And Virtualizer