I used the new toolbox (atbx) recently when creating a simple toolbox that links to a separate py file like I used to do with the old (tbx) format. I only recently realized that atbx is a zipped file with a number of py, json and other files. It also seems like it might work better the Python Toolbox (pyt) for managing my python tools. But, I can't find any actual documentation about how to use and format an atbx file to do more advanced coding. Specifically, I was introduced to the UtilityDataManagementSupport toolbox that has some useful tools. If you "edit" any of the tools, there's just a stub function that calls the internal tool that does the work. There are a number of internal py files that have the actual logic for executing the tools. But the only option I see to work with atbx files in Pro is to add a script and edit the logic for that tool directly. How do you add additional classes or common code that all scripts might share in the atbx? Is it just a manual thing of unzipping the atbx file, adding your files and then recompressing? Seems a bit awkward to manage and test this way. I'm mostly surprised that there is apparently no documentation about what atbx is and how to work with it.