（積ん読）PEP 518 – Specifying Minimum Build System Requirements for Python Projects
This PEP specifies how Python software packages should specify what build dependencies they have in order to execute their chosen build system. (Abstract)
Specification
tool table
The [tool] table is where any tool related to your Python project, not just build tools, can have users specify configuration data as long as they use a sub-table within [tool],
e.g. the flit tool would store its configuration in [tool.flit].