Edit: to add more detail.
If you look in the project for some files that have been updated recently, such as this one, the feature list includes some numeric codes at the top, which are the same ones StagingTool uses.
The ones without any symbolic name at all, I believe, are ones that have not been determined yet what they do.
Where can I find the tool?
Probably omitted as "an exercise for the reader" since it's legally grey. And a difficult exercise. I cannot find it at all
There is a link to it from this article:
https://mspoweruser.com/how-to-use-staging-tool/
Not the exact StagingTool, but the GitHub project mach2 that's linked to in the article supposedly supports many of the same features as StagingTool, I guess kind of an open source clone.
Edit: to add more detail. If you look in the project for some files that have been updated recently, such as this one, the feature list includes some numeric codes at the top, which are the same ones StagingTool uses. The ones without any symbolic name at all, I believe, are ones that have not been determined yet what they do.