The current wheel 1.0 specification was written over a decade ago, and has been extremely robust to changes in the Python packaging ecosystem. Previous efforts to improve the wheel specification were deferred to focus on other packaging specifications. Meanwhile, the use of wheels has changed dramatically in the last decade. There have been many requests for new wheel features over the years; however, a fundamental obstacle to evolving the wheel specification has been that there is no defined process for how to handle adding backwards-incompatible features to wheels. Therefore, to enable other PEPs to describe new enhancements to the wheel specification, this PEP prescribes compatibility requirements on future wheel revisions. This PEP does not specify a new wheel revision. The specification of a new wheel format (“Wheel 2.0”) is left to a future PEP.