Modules in this section implement low-level APIs. These modules fall roughly into three categories:
fundamental utilities such as collection. Many add-ons are likely to want to use modules from this category.
privileged modules that expose powerful low-level capabilities such as window/utils and net/xhr. You can use these modules in your add-on if you need to, but should be aware that the cost of privileged access is the need to take more elaborate security precautions. In many cases these modules have simpler, more restricted analogs among the "High-Level APIs" (for example, windows or request).
These modules are still in active development, and we expect to make incompatible changes to them in future releases.