Katana (1).dll -

A compiled C++ plugin used to modify scene graph data .

Katana does not automatically search your entire computer for plugins. You must tell it where to look using : OpWrite — Katana Developer Guide - Foundry Learn Katana (1).dll

In the context of Foundry Katana, a .dll file (on Windows) is typically one of the following: A compiled C++ plugin used to modify scene graph data