A TMO file is rarely a typical "document" like a Word file, PDF, image, or video that people open, read, edit, and save, because those human-created files usually represent the main source of information, while a
TMO file is instead software-generated and meant to load quietly in the background as part of a program’s workflow, storing things like cached data, motion info, or other derived values that help software run faster, with the true original data usually living elsewhere and the TMO simply acting as a supporting artifact.

Because of this function, the ".TMO" file extension doesn’t describe a single shared format, allowing different programs to assign completely different meanings and structures to it, so two TMO files from different software may be entirely unrelated, which is why no all-purpose "TMO viewer" exists and why double-clicking one causes Windows to ask for a program—an indication that it wasn’t designed for user interaction; and while a text or hex editor can open it, the contents are typically binary and useless without the program’s logic, making manual changes dangerous enough to corrupt the file and trigger crashes or strange behavior.
This is why removing a TMO file is generally a better choice than trying to edit it, because many TMO files are throwaway support files that don’t store irreplaceable user data and can be rebuilt automatically if missing; when an app starts without its expected TMO file, it often recreates it from other information, causing at most a slightly slower launch, but editing that file can corrupt it beyond recovery, and its directory location provides clues—temporary or cache folders often contain rebuildable TMO files, installation or game data folders usually hold required ones, and project folders contain files meant to be managed only through the software itself.
The most helpful way to interpret a TMO file is as a working helper file instead of something meant to be opened like a document, resembling a cache file, compiled shader, or index that supports efficient operation, leading to the better question: "What program produced this, and am I supposed to interact with it?" because modern software stores intermediate, expensive computations in temporary files like TMOs so it can reload quickly and run smoothly, using them as shortcuts for faster execution.
Another major reason is the separation of concerns, where developers categorize important stored information as information that must be preserved and derived data as information that can be recreated, with TMO files typically being derived, giving programs the flexibility to rebuild them and enabling safer crash handling since invalid or corrupted TMO files can be discarded on restart and regenerated from reliable inputs, lowering the risk of permanent damage to user data.
From a software engineering perspective, these files facilitate smooth iteration and version changes since internal data layouts shift over time, and locking temporary state into permanent formats would
hinder backward compatibility; instead, TMO files keep that data disposable so programs can drop outdated versions and rebuild them automatically, and they also support automation by holding runtime snapshots or processed data that enable efficient pausing or parallel execution, with their replaceable design ensuring software remains fast, stable, and resilient through an erasable working scratchpad.